Interesting, you say that between 1990-2010 Russia was a great power, and now dismishing from that position ?They will likely take Ukraine, but long term this is a strategic blunder for Putin. The occupation and pacification of the Ukraine will not come cheap. The sanctions will cripple the Russian economy for years to come, and the decline of Russia from great power status will only accelerate. The Russians and their various constituent nations will become increasingly restive. Add to that an aging and increasingly paranoid Putin, and the West will have an ever easier time to set them up for regime change and possibly balkanization. China should be wary of relying too much on Russia.
Behaviour of any country doesn't support this theory.
And generally, why you think that the currently implemented sanctions won't came anyway?
In the past ten years random events, unrelated to Russia trigered sanctions, like poisonging a british spy next to the UK chemical weapon complex.