One would hope that the backlash from Russia's so-called allies would be intense, but don't forget what's in it for them too.
Russia is aiming at nothing less than a total realignment of global power, and bringing democracy down a peg or two (well, getting rid of it completely would be a bonus), and that includes promoting Trumpism in the US and it's bastard children Brexit in the UK and Euroskepticism in the EU. China and Iran are all in favour of all of the above, and India is regionally more sensitive to its neighbours than it is to 'the West'.
For all we know, they would not only turn a blind eye to a nuclear attack on Ukraine, but are possibly quite keen on the idea because they figure (perhaps correctly) that it's a free play - if the EU, UK, US and Japan won't/don't counter such an atrocity, then why would China condemn it?
I do, however, hope that this isn't the case. China (and everyone else for that matter) does stand to lose from this situation if they are not careful, and can still exert considerable (and possibly critical) pressure on Putin, and avoid the prospect of a global nuclear war.