Well meltdown might be a bit far but I take your point. Personally though would say in De Gea, Rafael, Jones, Smalling, Zaha, Januzaj and Welbeck there are immediate young players who can become big players for us and top class in their own right. Anderson and Clev might not ever become part of the first eleven but either of them would be a very good squad option to have,
Then in Evans, Nani, Valencia, RVP, Hernandez, Young, Carrick and Kagawa we have a core of players in their prime or entering it. I know Carrick is a bit older but we've seen players of his ilk really extend their careers in the position he already plays.
The older players who might be more effected sooner rather than later like Evra, Ferdinand, Vidic, Giggs, are still contributing well. We've not had the Giggs who was a flying winger for a number of years now and we've coped fine. Personally I would say that between them, when they play to their ability, Nani and Valencia have got the wings covered very well.
So for me there isn't much wrong with the team, I don't think we can put of investing in a midfielder much longer, particularly so for a Carrick alternative as at some point you'd imagine he might get a proper knock, however I think a creative player is more to allow us to compete against the very best rather than essential to us competing for the league, with the current teams City and Chelsea have, although that's no reason to stay static there.
The more immediate concern for me would be what happens with Nani and Rooney. I think these are two really important players for us, imo, with RVP our 3 best attacking players, they both had disappointing seasons but both can be massive over the season. Loosing them without getting a replacement would be a big blow. The team as it is now though for me has a lot going for it. It hasn't been great in pre season but personally I don't think people are really factoring in that we've barely seen any of the senior attacking players and been chopping and changing the defence a lot.