Funny that you posted that, I just found this:
https://www.globalsmashroster.com/fighter/KOS-MOS
https://www.globalsmashroster.com/franchise_search/Xeno
Fan run public poll for Smash wish characters. KOS-MOS is a long shot, but is a very well marketed and remembered rep for Namco and given Nintendo's current relationship with Monolith, I think it's more likely than some might realize. At least likely enough that I can dream.
FYI: Moved thread to All Xeno General Discussion since it's about getting Xeno characters into Smash. Though I debated the General Game board and the Xenosaga board (since you specified KOS-MOS) I'm not gonna over think it.
I don't know how much it will actually help but I retweeted your tweet. Godspeed!