My point is, we're still easily in contention for a top four finish. Not too long ago, we were sitting closely behind the first place and seemed to be on the right track. The worst decisions usually result from emotional overreactions, which a sacking of van Gaal right now would be. A manager taking over at the current point in time would require plenty of weeks to get acquainted with the team and implement his game plan.
We're not doing well and unless we seriously climb back up the ranks, van Gaal should be gone at the end of the season regardless. But as of right now, things, despite being bad, are still not bad enough in terms of the entire season to sack him.
The only reason to sack him now is if we viewed Mourinho as our manager of the next few years. I wouldn't be opposed to it, but IIRC Sir Bobby Charlton was one of the people who was completely against bringing him on.
Outside of Mourinho and Ancelotti, who is most likely gonna wait and see what happens at Bayern, there's no good alternative left.