Now that K. Rool is confirmed and characters like Ashley Chrom, Zero, Mimikyu, and Shovel Knight are deconfirmed Geno is really the only character left that placed high on polls for inclusion since Brawl that hasn't been addressed. It really does feel like it's not going to be long until Geno is addressed one way or another whether it be as playable or as an AT. I would put money on us having a clear answer by the next direct in either October or November.
Also I haven't gone back and looked as to whether this was addressed in this thread, but I saw an intriguing thread on reddit I wanted to share:
https://www.reddit.com/r/smashbros/comments/8sodaw/holy_f_i_know_what_the_figure_was_for_that/
tl;dr Sakurai bought a gundam figure as "research" for a character back before we knew there was going to be a new Smash title. Out of the list of potential fighters yet to be confirmed/deconfirmed Geno seems like he would be the best match for a character Sakurai would use a robot with a gun coming out of its arm to reference.