This is just like Megagross. Something that isn't broken at all is being considered for ban, simply because it "restricts teambuilding", "2HKOs everything", and "we want to see how the metagame changes". I will explain why those accusations are similarly false.
"It restricts teambuilding!"
That's almost irrelevant when literally every A+ & S tier Pokemon restricts teambuilding as well. You either keep them in mind, or else you will fail. Stop being lazy and put a Hoopa-U check on your team! I assure you, it isn't difficult...Any decently strong physical attacker at least max 127 base speed will do, and that's for scarf (mega bunny & bee). Specs have more checks than I can count, but Talonflame & Garchomp are my favorite.
"2HKOs almost every switch-in!"
So does Band Azumarill, Specs Chandelure, Band Rampardos, Band Haxurus, etc. Doesn't make them broken, and they are either faster than Hoopa-U, stronger, or have priority. Fact is, every Pokemon can only have 4 moves, and choice items locks you into a single move as a payment for increased speed or power. For example, Psyshock is a free switch in for every dark type in OU. A choice-locked Hoopa-U would normally have no choice but to keep switching out whenever it attacks, because it is just too freaking easy to revenge kill this "banworthy" Pokemon.
"We wanna see how the metagame shifts"
This is just a fancy way of saying "I don't have any real reasons to ban this pokemon other than to see what happens". That is just...*sigh*
We're supposed to ban something if it's BANWORTHY! Nothing more, nothing less!
I forgot to say, I choose no ban!