One way or another, I think the remaining DLC will speak volumes as to what Sakurai, Nintendo and SE's true intentions are for Geno. For example, if say:
-Geno doesn't appear in any way, shape or form, including via the already existing Mii costume, then one of those three entities flat out wants Geno dead. Period. This would be incredibly unlikely, and frankly stupid as far as I'm concerned, but it's the only conclusion we'd be able to draw from such an outcome.
-Geno appears as nothing more than his original Mii Costume, then Sakurai and likely at least one of the other two simply doesn't deem Geno worthy to be a full character but still wanted to make an easy buck and give a nod to his long-time fans.
-Geno appears with a newly revamped Mii costume of much higher quality a la Sans, complete with unique music tracks, etc., then pretty much the same as above but with a few caveats. Firstly, the increase in quality would mean that Sakurai genuinely WANTED to appeal to the fans and wanted to do more for Geno than just make an easy buck. Secondly, though, it would mean that either Nintendo or SE have expressly refused to make Geno a full character for whatever reason which could stand as a questionable omen for the future.
and
-Geno FINALLY makes full character status, meaning the stars aligned. In all honesty, I think the two most likely outcomes will be the second or fourth scenarios. At the very least, we should get the costume back. At the best, we obviously get Geno in full. Still, these are the only conclusions I could make from the given outcome.