I read through the forums, didn’t find the answer to this, so I’ll start a new thread.
When you ascend a troop, it goes up a rarity level. Rare to Ultra-Rare, Common to Rare, etc. When you use a gold key, you can only get Common or Rare troops.
So if you ascend a Rare troop, making it now an Ultra-Rare, can you still get more of those troops with a gold key? Or does your game version now view it as Ultra-Rare, meaning you can only get it with a glory key?
Yes. You still get those troops on gold keys even if the are epic, legendarie or whatever. 
Troops’ drop rates from chests are equal to their original rarity (and show up with the appropriate border to reflect this). But in any other part of the game, any troop that has been ascended will always be however high you’ve ascended them.
So your Rare troop that has been ascended to Ultra can still drop from Gold Keys and Glory Keys. Conversely, this also means that it will NOT drop from Gem Keys, because its not a real Ultra-Rare (the bare minimum from Gem Keys).
Cool, thanks for the fast reply.
Also, in case anybody is wondering: when you ascend a troop, the cost to raise its level does not also rise to match the new rarity. That is to say, a common troop will always use the level up scale of a common troop, whether or not you raise its rarity before leveling it. So a newly legendary goblin will cost the same to level up from level 1 as a regular old common goblin.
FYI! 
But a new Goblin will already have legendary rarity, so leveling only needs to be done once.
What I mean is, if you decide to ascend before leveling a troop, it will not increase the cost of leveling.
Great if its true!