Phoenix Wallet is not just a Bitcoin Wallet, it is also a Lightning Wallet, and that is a big problem since Phoenix Wallet opens the channels for you, which also means that those channels are soon going to be cut (or in Lightning Network jargon "closed").
I don't think most users are ging to close them.
It an app becoming unavailable in a store, it's not like suddenly is illegal to use it, if you have it installed you can still do so until it becomes banned and it would be a crime to do so, theoretically you can still install even samurai wallet right now if you have the source code, it's not a punishable offense.
Phoenix is just trying to keep themselves safe, they have a good business going around and jail time when you're making a few hundred thousand is not really attractive, nor is giving away all that money inflow!
What is going to happen with ACINQ channels and even with them, after all they might not be based in the US but still in the EU, so this will be just a breather.