Van Gaal is radically different from our past few managers in almost every conceivable way. He's not a hopeful young 'un fresh off some underdog European success like AVB or Ramos: he's been around the block, is vastly experienced and has won almost everything of note within the game while managing some genuine giants like Barca and Bayern. He's not an 'arm around the shoulder' manager like 'Arry or (apparently) Full-time Tim: he's a disciplinarian, who takes absolutely no nonsense and has no qualms about ripping players apart if they disobey his instructions. And he's not a 'let the players play' man like 'Arry or Jol: his tactical systems are notorious for being intricate and devoted to perfection in even the smallest things.
He's a cantankerous 62 year old with an enormous pedigree, a reputation for being intimidating and hard-nosed and a maniac when it comes to obsessive planning. We've never, ever hired someone like that, and doing so could either revolutionize the club or utterly sink it. For example, what of the players he'll be managing, the likes of Daws, Lennon, Defoe (possibly), Lamela or Eriksen? They've become accustomed to having soft-spoken or motivational types (even with the latter two, under AVB and now Sherwood) who are often more understanding of errors than contemporary managers would be. How would they react to a red-faced Van Gaal blasting an angry tirade their way for failing to make a precisely planned 62-yard-pass in the 37th minute after a precisely clocked 12 minutes of possession play? Actually, scratch that: how would they react to what would presumably be eruptions of molten fury over the mistakes they make on a frequent basis?
If I read our players right, they're not cut out for that, being a bunch of soft, quiet lads. Van Gaal could destroy them. But equally, I may be understimating our players or overestimating Van Gaal's bursts of temper, and in that case having a manager they would undoubtedly respect enormously helping them raise their game could turn them into steely, no-nonsense types as they buy into the manager's vision, which could very well revolutionise the club in the long-run.
Same thing goes for Van Gaal's lack of experience in England: all his life he has managed teams in countries that adhere to certain philosophies of considerable tactical complexity and deeply-held views of how the game should be played: how will this 62 year old adapt to the fast-paced, end-to-end whirlpool of tactical anarchy that is the Premier League? He could adapt very well, of course: you don't win the things he's won and manage the teams he's managed without large amounts of intelligence, adaptability and nous. But equally, he could be chewed up and tossed aside by the unforgiving Premier League like so many talented managers have been over the years, and we would be set even further back.
And both those things are still only two of several major issues that have to be addressed. He blooded youth players well at Bayern: would he be willing to do the same here? How would he get the notoriously fickle English media onside? Would the fans take to his decidedly no-nonsense approach? How would Baldini feel working with him? What would be his gameplan for those crucial first few months: defensive solidity first and foremost, which would mean recieving a barrage of criticism from media outlets angry at this foreigner taking over from free-flowing Tim, or the 'we'll score one more than you' approach, which would bring with it a high risk of bad results (and, by extension, fan discontent)?
So like I said, it could go either way. Lots of doubts will undoubtedly emerge should we appoint a polarising figure like Van Gaal, and thus it has the potential to be either a brilliant or utterly destructive move.
Personally, however, it's far too soon to be writing Tim off, and I'd be happy to return to this at the end of the season. For now, though, I'll do my best to avoid commenting on 'future managers' when we have one working hard to keep his place right here.