You're not thinking this through far enough.
If, and it's a big "if," if Putin did blow up his own Nordstream 1 and 2 pipelines, he did it so that even if he is removed from power, Europe is going to suffer.
His successor can't say to Europe "see, that evil Putin is gone, we're nice guys in charge now, so we can turn the gas back on and everybody will be happy again."
The destruction of the pipelines ensures that no matter what, Europe is going without Russian natural gas for a minimum of two more years. Two winters of freezing. Two years of reduced industrial output. Two years of economic hardship.
This was Putin's middle finger to Europe.
There has been talk, of course not verifiable, that people in the Russian government saw Putin as too soft on Europe.
Russia has tried to join the EU and was told no.
If Putin goes chances are you’ll get someone worse, not better.
A big opportunity was missed in the 1990’s to make a more peaceful world. Instead the US became more bellicose, Europe more authoritarian and Russia more corrupt.