The west is not the only party that would have to welcome a new russian leader - the russian oligarchs, as well as people interested in making money selling to the west, needs to be on board.
Putin can remove the temptation to overthrow him, and restoring normal relations with the EU (gas pipes included), by blowing it up - something that is currently not being used and serves to short to medium term value for putin. However, blowing it up, but hiding who did it, can sow mistrust in the NATO alliance. He might be betting that the germans would think the americans did it (or at least be suspicious). And if he was found out, russia can claim that they're within their rights to blow up a pipeline that belongs to them (aka, no real bad consequences).
Putin can remove the temptation to overthrow him, and restoring normal relations with the EU (gas pipes included), by blowing it up - something that is currently not being used and serves to short to medium term value for putin. However, blowing it up, but hiding who did it, can sow mistrust in the NATO alliance. He might be betting that the germans would think the americans did it (or at least be suspicious). And if he was found out, russia can claim that they're within their rights to blow up a pipeline that belongs to them (aka, no real bad consequences).