Putin is in a box, he can come clean on the missile attack and Russia will be relegated to an outsider in the world community or not cooperate and be persona non grata on the world stage.
It was the CCCP then, and they didn't admit to anything for a long, long time.
Everybody kept dealing with them. History teaches us things.
Putin holds a fair amount of cards. The natural gas pipeline is a key one. Europe depends on it.
I do not see that it would matter much if Putin through some pro-Russian separatists to the wolves. How would that change anything?