If they dont go with the Onyx plot, which I hope they dont... Onyx would be a terrible intro to the setting for new players, then they can have the Spider as they were up to twenty festivals, a clan of dishonorable samurai that care little for the virtues of honor but instead value personal power and ambition. Think scorpion, but being a military clan instead of a political and none of that "we protect the throne" nonsense, they are, at least on the individual level, in it for themselves.
In truth they could simply be a dark mirror of the lion. Story kept pushing them as "Shadowlands but not" during emperor which kept missing the easy way of doing it by just describing them as "Dishonorable Samurai". They are the servants of the descendant of the dark lord, the conquerors, and major power, of the colonies, and the masters of the dark path of shourido, which is the path of self. They value power and care little about the methods used to attain it. They care little for the honor of others and suffer the advantages, and flaws, of holding such a view. Their presence in the main empire is smaller, but as a clan they are tolerated, not just for the deal with the devil but for the endless goods shipped from the lands conquered by them. The fact that they are mostly in the colonies keeps them both safe from repercussions of some of their more devious actions, but also limits their plans in the empire directly. The distance that the colonies and the Empire has is an easy tool to keep them in line from a story setting, leaving them with a few port sitties in the main empire and ensuring their armies cant just march and cause a ruckus. Their thoughts and issues are constantly drawn to lands they seek to conquer and, like the unicorn, could become more cautious of the outside threats, except instead of meeting gaijin with compassion they meet them with the xenophobic sword that rokugan is known for.
Let a few clans have reasons to keep them around, like Crane, who are happy to trade for the exotic and beautifu, not caring for the Spider's ways because they are so far in the colonies. Let the Mantis, with their ports and trading, find a strong relationship with the Spider like we have been having for the past few years. Have the Unicorn see them as another clan that understands the threat of the Gaijun and share the vast lands of the colonies with them, like we have had for a while as well.
Spider works fine if you just tone down the "omg eat babies" view that, funny enough, they haven't had for the past few years anyway. Until Twenty Festivals the Great Clan Spider have simply effected and manipulated the empire through mostly political methods, the Susumu gaining an insanely close bond with the Imperials and the heirs conflict were both Spider plots to effect the empire. Hell Kanpeki's plot to take the throne didn't even involve armies, just marrying his kids into the Empire's royal line. Its why the rush into the Onyx plot angered a lot of Spider players as Kanpeki giving up and tainting everything seemed actually out of character.
Spider can still have evil plots, but they are more subtle and interesting and if we want a game with samurai clans infighting as its purpose then keeping spider is perfectly fine. People overact to the spider in a setting where Kisada broke every oath and the entire point of his clan and walked away pretty much with no consequences while the Great Clan Spider for the most part never got close to that kind of nonsense, the worst we had was the ninja, and they were pretty much in the same boat as the Scorpion, no one knew so it didn't matter. Besides that we have the tainted, mostly dying off, the Sohei without their corruption, the new generation of Daigotsu Bushi like Atsushi and Takahide, and the Susumu courtiers that exist with massive clout and ties to the more powerful families in the empire, making them difficult to reproach. Spider could have interesting roles, like cruel but efficient magistrates, mighty conquering armies,
Talking about crab, the whole crab vs spider thing is just too pushed. Turn on the pits again and let the crab be too busy with their wall to care. I'm freaking tired of the plot of crab CONSTANTLY trying to fight the spider, its just boring by this point. Spider's perfect foil in the empire is lion, not crab. Crab and spider atre too similar as pragmatic military factions, one is defensive and good, the other offensive and bad, to really create that drastic contrast that rivals should have. These factions have next to no reason to interact in the ways they do if the pit was operational so they just need to retcon the deal or alter it in a way to allow the pits to remain active. The crab was made for holding the wall against armies of monsters, give them back their monsters and move on.
Spider, as a great clan, could be a perfectly fine and enjoyable faction. people just need to stop harping on poor story choices made years ago by the formal owners. This setting really lacks real "evil samurai" without them. The scorpion are villainous, but only as part of their act and are really "loyal to the throne". The Mantis are gung ho more then villianous and all of the other clans are only villainous when taken to their ultimate extremes. Spider can fill the role as the basic evil samurai, an easy message for both new and old players.
Shadowland Hordes would be more interesting in my opinion if they found a way to make it into seige style decks, which have been shown to be really fun and interesting. that way they can make Shadowlands as strong as they want, create an interesting story adventure through its cards and deck, without worrying about factional balances or problems with stories, just make it known that, when the Oni roll in, the empire unites, hell even the spider as what good is an empire of ashes. That way the major Big Bad factions, be it Jigoku, Yodetai, Kolat, or otherwise can be exactly that, BIG and interesting, released as expansions and adventure sets while there remains the ability to just have the clans pit fight one another.
Setting that up would only require simple changes to Daigotsu and how he rules the realm of evil, make him go the way of Fu Leng, and become a mad, dark God and let Kanpeki learn that, perfect reason to have Spider and Jigoku not always team up and even be opposed.
Go back to the SH, the vote showed that given the choice the majority of Spider players prefer to BE the Shadowland Horde that a great clan.
But it didn't... at all. In fact it showed only that 41% of the Spider wanted the only path that made them hordes. The other two option (consisting of two different paths that both ended with fighting Jigoku and not returning to hordes) collectively held 59% of the vote. There is no way to interpret that the MAJORITY of spider fans wanted to go back to hordes based on those numbers. If that is how we are classifying these numbers (Becoming hordes vs not hordes) then the correct way to view them is that more then half wanted to NOT be hordes.
The story path votes for the clans led to choices that did NOT hold the majority of the clan's overall votes for all of them. Every winning vote had less then the majority of those fan bases supporting it. They really all should have been 2 options each and just judged it based off of that.
Now, some might have argued that if SAA didn't exist Hordes would have won out massively, but that is mere speculation by this point and the numbers are as they fall.