In reply to elsewhere:
Catch-22 for the man. If he stays away he's still in danger (see Litvinenko and the Skripals) and in a weaker position to oppose Putin, the reason he's in danger in the first place. If he goes back, he's in more danger, but also may be better placed to oppose.
Either way, reckon Putin will give it a little while until he tries something again. He likes his plausible deniability and won't get that if he offs him immediately. One thing is true though, unless Navalny does a Rodchenkov, he will not be safe no matter where he lives.