Here is my prediction -- Russia does what it wants with Ukraine because of immense military power, and NATO countries + US observes from a distance because of the lack any vested interest in Ukraine. Germany in particular has a financial incentive (oil pipeline) from Russia, but even if they didn't, Germany will not have gotten involved anyway.

The solution is for Ukraine to maintain their own sovereignty. This is either through military action or by making concessions to Putin's demands, major one is removing itself from the West/NATO.

From the looks of it, there is no hope in diplomatic resolution. I've read recently that US and Russian officials cannot come to any agreement; war is inevitably the answer.