I don't know. There are many different takes on the situation I hear and read, and I'm not sure what to make of it.
In theory? Certainly. The Russian elites believe the collapse of the USSR was the "worst catastrophe in the 20th century", Putin even literally said that. The USSR's influence reached westwards to East Germany. And Russia is following a "Machtpolitik" that wants them to become a world power once again -- and in order to achieve that, it has to break American influence in Europe and the Middle East. So in their wildest dreams, they have designs beyond Crimea without any doubt.
However, I am not sure about Russia's military capacities (though I suggest it's not as broken as many keep repeating, as if this was still the 90s and as if the West hadn't massively disarmed too), I don't know how realistically the Russian elites view their own capacities and situation, I don't know how many risks they're willing to take. In the ideal case, they know very well that attempting to realize their abovementioned "wildest dreams" is unfeasible and unprofitable and thus are very well content with Crimea.
On the other side, and I don't know how far this goes into conspiracy theory territory, you can read from both American and Russian sources (such as Zbigniew Brzezynski on the American side and high-rank Russian militaries) that both sides are fighting a geostrategic war: The US are doing their best to roll back Russia (and have been doing so at latest since Yugoslavia and NATO enlargement 1999), trying to get the former Soviet states out of Russia's sphere of influence, and attack Russia's influence whereever they can (first Serbia 1999, Afghanistan 2001, Iraq 2003, Ukraine 2004, Georgia 2008, Syria 2013 and now Ukraine), encircling Russia. Some Russian strategists even claim it is the American goal of destroying Russia on the long run, and it's a fight for the mere physical survival of the Russian state whether Russia manages to escape this Western entanglement. Brzezynski IIRC even said that on the "Eurasian Chessboard", Russia's capacity to ever rise again and defend itself stand and falls with its power over Ukraine.
If that's true -- or at least when that's how Russian strategists view it --, I'm afraid Russia is willing to take a damn lot of risks and even do very stupid things to make sure it will even "survive".