Dragonite SW/Hurricane

Due to its rarity, I would always keep a Dragonite, no matter what.

Plus you never know what they are going to do with moves in the future. It would seem that Niantic like to change things every so often.

Come on. A 90+ Dragonite? Why would you transfer him. It's a 90+ Dragonite. It will be useful as both defender and attacker regardless of moveset. If you asked if you should invest dust and candy in it, then I would understand your dilemma more... but not whether or not you should keep him.

I'm in the same situation, 40IV points, same moves. But it's the first Dragonite I can evolve (I'm level 31) so I don't expect to be able to get another one before many months.
I'll power it up for gym position, was not going to use it for attacking anyways.

Throw him in the gym. It doesn't matter what moveset he has with something attacking with Piloswime, Cloyster, or Lapras. That Nite is a goner in 15-30 secs depending on moveset and player usage. 90% IVs should mean around 3K @ lvl 30 that's enough to be in most gyms.