If Ukraine turns toward the European Union and the West Putin may well move to seize Crimea.
It is the only region in Ukraine where Russians are in the majority, and there is the critical naval base at Sevastopol that serves as the home of Russia's Black Sea Fleet and gives the Russian Navy direct access to the Mediterranean Sea. Russia has a lease agreement with Ukraine that allows its fleet to remain at Sevastopol until 2042.
There is ample precedent to believe that if Putin and the Russian establishment believed that Ukraine was slipping permanently out of their grasp, then Russia would find a pretext to seize Crimea. Russia has made it quite clear that it considers the former Soviet Union to be a space where it sees itself having wide latitude for maneuver.
Bob C