Second possibility is annexing Eastern Ukraine. But then he faces the strong probability of a war and the ending of Russian trade with the West.
I still think it's all about Russian access to the Mediterranean. Same as with Syria where he is propping up the regime to secure a Mediterranean port for his navy.
Methinks he sees these revolutions as a quiet method of undermining Russian power.
All the stuff about protecting Russians is pretext to protecting a key artery from the River Don, through the Sea of Azov, past the Crimean Peninsula, through the Black Sea and the Bosporus to the Mediterranean. Just as important today as when the Vikings used the Don to travel from Denmark to the court of the Byzantine emperor.
I suspect Putin's had his eye on the Crimea for years.