I love Shadowlands, but not as a playable, competitive faction.
What I would like to see is a multiplayer version of L5R done in a fashion similar to the Arkham Horror LCG.
A 1-4 Player Cooperative Story-Driven Campaign LCG where players start with basic cards and are able to advance their decks through gaining experience.
This is a great place to journey into the Shadowlands to explore dark evils and fight off evil Onis, Bloodspeakers & pesky Goblins.
Of course, there would be plenty of Court intrigue and opportunities to prove one's mettle and honor in defeating internal threats to the Emperor.