We can hope that Putin will be satisfied with Crimea, but it looks like Moldova is next on his list. One can hope that that will be all that he takes and that he wouldn't for example risk invading Lithuania, a NATO country. But on the other hand, what could be a greater victory for Putin and his dream of breaking the west's dominance than invading a NATO country Crimea-style, without a shot fired? It would shatter the idea that NATO is a strong and relevant player in one fell swoop.
The thing that is both hopeful and frightening depending on how you look at it is that Russia's neighbors and Russia are both dependent on the trade of Russian gas. The neighbors for their survival and Russia for it's trade balance. Whatever he does, Putin is probably not going to risk a shooting war that could destroy gas pipelines and ruin trade relationships.