France has nukes, so this isn’t going to be Hitler 2.0 with Putin posing by the Arc de Triumph.
There are several ex-Soviet countries that are NATO members, so that’ll be the real hot spot if it gets there as the US et. al. will be required to act militarily in their defense (in theory).
If so, expect Korea, Japan, Taiwan, Turkey, Poland, Hungary, Saudi-Arabia, Iran, Iraq, Egypt and so on to test nukes within the next 10 years.
Or, to be charitable, since India and Pakistan both tested nuclear weapons and nothing happened.
Which is why the Ukraine should have been accepted into NATO (and preferably the EU too) in 2015 or so.
Though, now that the invasion has started (again),
the alliance is already pretty consolidated. I think putin sees a NATO ukraine as more dangerous imho - esp. if ukraine becomes more and more democratic.
The invasion would be successful if the west does not deploy troops and intervene. I say the west has already failed, and this sets a precedent to which china would follow.
And if the west waits for too long, the military edge that the west has would diminish. Unfortunately, the public is reluctant to commit to war, because in the minds of those who are used to peace, diplomatic solutions seems to be the only cost they're willing to pay.
I agree that there are difficulties in developing arms in peace times, war can be a driver of innovation. But it is not the only one and there are preferable alternatives, even if arms suppliers see that differently out of egoistic ambitions.
A civilian population rejecting involvement in arms manufacture is preferable to one that calls for a war.