Who knows, if the situation causes him to run into financial trouble, he might be forced to come back out of retirement and have at least one more fight that would set him up for life.
Meanwhile there are rumours about Chandler getting an offer to fight Islam in October.
It's all starting to look like we might see McGregor Vs Khabib 2 at the end of this year 
Khabib would beat McGregor again without a doubt, but this fight will never happen 
I am sure that Khabib didnt keep all his money in Russian bank accounts and local real estates, but this is great example why Bitcoin is important.
I think that whole situation is connected with some terrorist attacks, but Khabib just learned that he doesnt own his bank account and money that was in there.
I also think that Khabib will just choke the shit out of Conor "AGAIN".
Conor will just say things like "I will fooking punch you in the face like shit, blah blah blah", but we know how good Khabib is, and how expert he is in his current playstyle which is more of grappling.
Anyway, like what you said, I don't see this happening as well, and with Khabib's situation, I don't know the exact situation about him, but I hope he's still okay. I don't also think that it's only tax that's the problem here, but there's a deeper problem. Maybe something related to criminals, or some gangs out there.