A key thing to note along those lines is that diplomacy can be a lot more effective with Russia than it was against the Soviet Union just with economic pressures because Russia is so much more integrated with the world than the Soviet Union. The SR only "traded" with itself and Eastern-Bloc countries and a bit to China so actions beyond shadow/proxy wars was kind of limited. Today the threat of freezing assets and disallowing visas is much more of at potent because their wealthy have investments in projects in Europe, send their kids to US and European schools, and like their freedom of movement to take a vacation in the Caribbean. Interrupting that is easy and having the wealthy of your country complaining doesn't strengthen your party politics.
As already mentioned counting on Russia's energy to silence critics is probably not going to work due to the shifts in supply stocks mainly from Canada and US. If nothing else, lots of Europe itself just will not want to trade with Russia because it looks like bad business. Whatever good will Russia had left in Ukraine has evaporated into hardline partisan politics and the rest of Europe will soon follow if they keep going this route.
I ask again "Is it worth it for Russia?" They gain a little country and secure some naval bases but they lose a bunch of trade and global prestige they tried to build from Sochi Olympics. If this was just about monkeying around with Ukraine to get a favored government installed that would be one thing but because of their actions and players in proxy for them it is not screwing around continental and international trade. To that end the US and EU should be doing everything possible to ratchet up the "cost" of going through with it.
ps. It should be noted that everyone has forgotten whats-his-face that started the whole thing.