I wouldn't take him back, honestly.
I've never found him a master tactician (his teams' successes were always founded on a few basic football concepts and the almost shamanic connection he was able to establish with his players), and now that he's kind of lost his mojo, he's simply become the caricature of his former, winning self. His teams play a boring, uninspiring, and often (especially against good opponents) passive football, and whenever things don't go his way, he starts bitching in the post-game interviews.
My opinion is that he should seriously look inside himself and start considering what he really wants to do in the next ten years or so. If he wants to continue coaching clubs, he should definitely take a break (one, maybe two seasons) and use that time to bring himself up-to-date about football tactics, because frankly it looks like he's stuck in the past.
As for his present job, it doesn't take a crystal ball to realise that his time there is running out... He will definitely not be there at the start of next season, but I wouldn't even rule out the fact that he might (be forced to) quit midway through this season. It was an ill-suited match from the start if you ask me, but it was his long-time dream that of filling SAF's boots, so he couldn't turn down the opportunity... The only thing I (partially) agree on with him is that the club makes a shit-ton of money every year and should therefore spend more in order to improve the roster, especially if you want to keep pace with a powerhouse like City and a Liverpool that finally seem on the rise again. I wrote "partially" because, even though Woodward is a cunt and all, a good manager should also focus on developping the players at his disposal, which frankly doesn't seem to be one of Mourinho's main concerns at the moment. Some players might not be United material, granted, but please let's not act as if he was coaching Chievo Verona.
That being said, I realise nostalgia, combined with the constant disappointments that marked our post-triplete era, may induce people to overlook all the reasons against his return. However, I think getting him back would be like Williams re-signing Mansell and Prost in hopes of winning another WCC. It simply doesn't work like this. People change, times change, and you can't expect a thing, however wonderful it was, to work again simply because it did ten years ago.