The MLBPA fought drug testing because they were the ones cheating. I don't condone it, but I understand it. By the time of the last contract between the union and owners (2003?), steroids were a big issue. Selig did everything that he could do to make the issue go away without forcing the players to stop juicing.
So many of MLB's star players being exposed as cheaters is the inevitable outcome of Selig's actions. He put the short term interests of baseball (5 years of more record breaking offense) ahead of the long term interests of baseball (massive, long-term fan anger).
The real question is "How will fans react in April?" If it's anywhere near as ugly as it was after the strike, Selig is in real trouble. Hopefully, if that happens, the owners will see the logic in having a real commissioner and not one of their own.
I remember the first Astros home game after the strike. Drayton gave away every seat in the Astrodome, and there will still 20,000 no shows.