a domain is just a domain. poker site domains get seized; they pop back up on .ag or something similar.
I remember last year that I offered BTC-E the btc-e.co domain that I was holding, but they gave me no answer. Unfortunately, due to a noob mistake from my side, the domain got expired as I by mistake disabled auto renewal. After noticing that the domain wasn't sitting in my registrar account, I checked, and yes, it got registered by someone else. In this case, it would definitely be a great alternative domain for BTC-E to operate from, if they are ever planning to seriously come back.
the important thing is the money. how well was the fiat hidden, how much can they move (i.e. get into crypto and USDT or similar), and was much crypto lost? this is what matters. if btc-e really wanted to relaunch, they could do so as a TOR hidden service or play whack-a-mole with domains like the pirate bay did.
It's safe to assume, or at least the best option in order to not get disappointed, is to completely forget about fiat. The only thing that there is left to focus on, is what they have sitting in their cold wallets. Authorities can size everything they want, but there is no way they will ever find out where the cold wallets are hidden, unless Vinnik (in case he is really the co operator) opens his mouth. But hey, even if that is the case, the cold wallet funds are moved to a different location, that's pretty much guaranteed.