This seems like the same mistake Putin made:
The West won't care when I destroy Grozny.
The West won't care when I fight for Ossetia.
The West won't care when I annex Crimea.
The West won't care when I invade Ukraine.... oh.... ****
Not saying we should take the flapping of Moscow seriously every time, but we shouldn't assume there isn't any line anywhere either.
We definitely should not be intimidated, etc. by the stuff Russia/Putin is coming out with but we shouldn't just assume it is all empty promises and something to laugh at either. Putin will eventually act, if he can find a way, his hands have been somewhat tied with this situation with the realities of retaliation but that doesn't mean he has forgotten or won't ever do something. People often ignore the subtext in his speeches.
Something which might be a problem in the longer run as well is the "true believers" who've bought into all the anti-West stuff, etc. who might take it on themselves to act or deniable assets sponsored by the Russian state to act against the West - which might include supporting the likes of middle eastern terrorist organisations.
We need to be wary of asymmetric warfare and not be blindsided by Russia or China doing something we wouldn't think they'd do because it would be unthinkable or unconscionable in the rest of the world - not a great example but for instance despite the outwards appearances Russia would have no problem sending children to fight in their wars, etc.
One thing which is unlikely to happen is the use of WMDs/NBC weapons in a way which could come back on Putin/those in power in Russia, except maybe if his back was to the wall.