Yeah what comes later is the hardest bit to figure out, a total puppet regime or occupation doesnt seem like it will work very well. There may be other possibilities, such as leaving certain government figures intact and so not going for full on puppets, but getting that government to agree to various Russian demands in terms of levels of western integration, some autonomy for eastern regions, not building a strong military, etc. Russia could easily miscalculate how well such things will work though, agreements made under extreme duress may not last long. Perhaps they've learnt some faulty lessons from Georgia, where the invasion of that country managed to subsequently massively erode the political support of the Georgian leader who had been a thorn in Russias side. I've not got many clues about any of this at the moment, beyond the obvious stuff about how well the Ukrainian leadership have done so far. People in Ukraine will obviously take Russia threats seriously in future in ways they did not previously, but what the longer term consequences of those fears are remains to be seem.