He's laid the groundwork excellently for a successful season next year and possibly for a few seasons afterwards. But I don't think he's the right person to take advantage of that fully.
He has thinned out a bloated and overpaid squad
Nope, most of deadwood is still here, and those who aren't we're still partially covering their wages.
He's reduced the average age of the squad dramatically
What exactly is that supposed to prove? Other than the fact we now clearly lack some experience.
He's coaxed great football out of Fred
He gave him a run of games, mostly because he didn't have other choices and now Fred is performing the the expected level. Not really an outstanding achievement.
He's overseen the emergence of McT as a proper class footballer with bags of potential still
No, that was Jose, not Ole and the jury is still out on McT, he seems like a good squad player, a Darren Fletcher if you will.
He's overseen Rashford's break out season
Rashford's breakout season was under LVG, he's currently, or was until Ole's mismanagement ruined his season, having a very good spell, but there is zero evidence that it's because of Ole, but rather just natural progression for someone of his talent. Also I would wager some aspects of his game have not really improved, his decision making is still "frustrating" at times.
He's brought through some very talented youngsters and integrated them into the first team very well
Which ones? Greenwod and Williams? Greenwood as talented as he may be, hasn't really set the PL on fire and Williams was more of a necessity because of injuries and Shaw is still often preferred to him. Which other talented youngsters were given a chance? None, even on the odd occasion when we were winning comfortably, Ole choose not to bring on any of them, despite having them on the bench. Even Klopp, has given more chances to youth this season in various competitions.
His squad management has been good, unfortunately his game management has been very erratic, some very unfortunate injuries, with Pogba, Rashford and McT in the team I think you'd be a good 6 points better off, but injuries happen to everyone and this season United haven't been able to cope with them. I think people will look back at Ole's tenure and see that he laid the foundations for success, but wasn't able to take advantage of that.
His squad management has been absolutely terrible and resulted in a thin, injury laden squad. He spent a fortune on defense with zero effect as we are worse defensively as last year. The one defender he let go is now the best defender in the Italian league while his replacement is struggling to live up the price tag. Also this hyperbole that injuries are to blame is just that, as last year, with all those listed available, we were still crap. There are no foundations being laid here, only lowering of expectations.
That's why my vote is keep until the end of the season and then replace.
I'm fully aware that we're stuck with him till the end of season at the minimum, but with the damage he's doing to the team, he should be fired with immediate effect, regardless of availability of a more permanent replacement.