Not if he is finishing in the top 4, Van Gaal got sacked despite winning the FA cup as he finished 5th.
It's a funny one.. I think Man Utd have been picking wrong managers at the wrong times and not been great in the transfer market. So hence Moyes, Van Gaal and Mourinho all underperformed.
OGS has probably been about par for Man Utd. Personally I don't think he's good enough to elevate Man Utd to compete for the big trophies but maybe they just want a bit of stability with how poor they've been in recent years.