Makes sense to be fair.
Truth be told, Darren is quite some ways off being a first team regular, and if we acquire more talent in the upcoming windows, he'll be pegged further down the order. Ideally the vice-captain should play week in and week out at a consistently high level so that he can fill in as active captain if the first choice is injured, suspended or substituted out of matches. Carrick embodies that criteria perfectly. Additionally he's our 3rd longest tenured first team player after Fletcher and Rooney, is quietly cerebral so he can relay the system to the troops, is massively respected within the squad - the likes of Wayne and Robin speak in glowing terms of him and his calm calculated demeanor, is a model professional and offers a wise head which becomes even more important in terms of providing uniformity through a period of transition allied with the departures/ retirement of Scholes, Giggs, Neville, Rio, Vidic, Evra in the span of 2-3 seasons.
As for Fletcher, I don't want him to be sold or loaned or for him to ask for a transfer. Might be a romanticized notion but he's a United lad, has been for 15+ years, is an example both as a professional and as a human being, still has a lot to offer despite the waning fortunes as player and will be vitally important as a voice of reason in the dressing room. Darren has spoken numerous times of being a manager once he hangs up his football boots. So with that in mind, he should be elevated to a player/ coach in the vein of Ryan. Would be a real head-start for his potential managerial career at just age 31. He could fill in as and when required on the field but his influence would largely be felt off it. He's doing his coaches' training right now so it would be the ideal apprenticeship for him in terms of being mentored by one of the most forward thinking tactical brains of the modern era and helping out with the youth teams or scout opposition clubs. It's just the perfect opportunity foe him - when life gives you lemon, make lemonade.