They will hold their ground because they are the legitimate military force in that territory. Crimea is part of the The Ukraine, and the United States does not recognize Crimea as being an independent state nor will it recognize Crimea as part of the Russian Federation.
They will hold their ground. Because we're coming.
The region will polarize to NATO's court now. There have been talks of Sweden now joining NATO as well as the bolstered NATO force that will start military war games in Lithuania to the border of Russia this month. Around 15,000 NATO forces and Naval, Air Forces will be sent there, in addition the participation of Sweden's Forces, which is not normally part of NATO, as a contingnent of the Nordic Battle Group.
Russian Federation has isolated itself , and Moscow's foray into Crimea will be utilized as pretext for Baltic, Nordic states in addition to major NATO partners to greatly increase defense expenditure to contain Russia and quash it when the time comes.
The long term strategic consequences....will be to OUR favor.