There will only ever be one SAF. No one (based on current approaches) will get close.
JM has never been at a club long enough to do the one thing that SAF stands above everyone on - building and rebuilding squads while still getting a high level of performance out of them.
SAF always had a balanced squad in terms of age and experience. Eg, when Rio and Vidic were past 30, he bought in Smalling and Jones for his next squad.
I am going to give JM some credit for playing some youth players this season, which has been a change from the past.
It will be very interesting to see who he signs in the summer - what age and experience they are, and who leaves.
Carrick, Zlatan and Rooney are the older players, so ones that are 20-23 yo to replace these guys are key. They may not be ready now (unless one is Greizmann, then i think he is good enough haha). Young seems like he will leave too, so another 4 signings in the summer of a fwd / winger, another fwd, a defensive mid, and a fullback - and JM will have a great squad and will be close to rebuilding at the same time.