Who isn't ignoring GC these days? Everything coming to GC Nintendo is involved in some way, from FF:CC to MGS:TS to heck, even Madden...
I don't think ONE company could change the forutunes of GC. If SquareEnix was to make more games for GC, not much would be different.
All I've heard is that the main line of FF games (all that really matters) would stay only on Ps2. And the reason so far they've stayed away from Xbox is because SquareEnix is a very Japanese company, where Xbox does aweful.