In recent years, Gamescom has been host to things like the announcement of the PS4 launch date, Mass Effect's console exclusivity coming to an end, Tearaway's announcement, Command & Conquer being rebooted (since cancelled), things like that. Gamescom is actually now a bigger show than E3 by a long way in terms of impact, and a lot of companies spend more actual money on their Gamescom presence than their E3 presence. Of course, Gamescom is a public show.
With that said - Square has debuted a number of things there in the past, though all Western. Deus Ex: Human Revolution had its first live gameplay demoed there, for instance, after having CG and things at E3.
Nothing's impossible!