39 minutes ago, Copes said:

I think both factions will appear eventually, but need another movie to give us enough material to really justify their existence. The biggest challenge is that the two movies (TFA and TLJ) happen back-to-back as opposed to several years apart like previous trilogies, so we essentially see the same characters / battle / gear.

Not only that, but prior to Episode 7, it was a Cold War state with no real conflict between the two factions. The stories happening before Episoe 7 is more about politics and investigations than open conflicts. Until they blew out Hosnian Prime, the First Order was mostly operating in the shadow.

As long as Episode 9 is not out, I don't think anyone can touch the events between 8 and 9, to leave complete control to JJ for the last part of the trilogy. Once Episode 9 is out, we'll start getting content that happens between both movie, and probably after 9 too. But until then, Resistance can't really get more than what was seen on screen. And at the end of Episode 8, there is not a lot of them left, except for some operative that was out for missions during the event of Episode 8 (like Snap and Jess).

I'm 100% sure that we'll see both factions from the sequel, but not until we've seen Episode 9.

@OP

Would I buy? Yes.

HOWEVER I'd like FF to flesh out any era they do before going to another. I keep hearing that the Clone Wars are going to be a thing in Legion within the next year, and that's great, but how about we flesh out the original trilogy era first guys before moving on? I want Hoth rebel troopers and Sandtroopers (maybe even on Dewbacks!), I want Ewoks to really help recreate the Endor battle in RotJ. I want Tantine IV/New Hope Leia, Rotj all-black Luke, Lando-frickin-Calrissian, non-Endor Han, etc. If you start reaching into the EU there's soooooo much more just from that era they could do.