this would be an insane decision
Smash's probably pinnacle of success and popularity (despite I believe higher sales on the Wii version because of how many owned that console) was on the Gamecube, people are stubborn and dig the old Gamecube controllers (me included). let's be honest they just have a great layout and balanced feel to them
they are selling for pretty outrageous prices right now (the controller Wii U ports) so Nintendo would be dumb to stop manufacturing. either confusion in communication or possibly being sold at exclusive locations I would imagine
also that can't be true about certain Amiibos already being dropped (no wayyyy) way too fast for that to happen