All of this, this poll is terrible :(.
No it was said in nintendo direct that both teams are involved. That said I'm not really sure who was given more creative control between the 2 so I can't say how big the team will be. Surely neither will use their whole teams for the cross-over because I don't think that ever happens. I also very much doubt this stops wiiU from getting another mainline FE game, when has a cross-over ever done that?