You make an excellent point about the WR position. If the players on the 2012 opening day roster are Welker 31, Lloyd 31, Branch 33, Gaffney 31, Stallworth 31, and Slater 26, it will be the oldest position - by far - on the team.
(I'm including Slater, as a WR because that is what he is listed as.)
I love that group for what it does in 2012 in the slot and outside for the offense, as well as what it means for Brady to have five/six WRs he knows and can trust (presuming Llloyd works out.) I do not think anyone will criticize Belichick, the GM, for putting that receiving corps on the field this year.
It creates the need for an overhaul in 2013 at that position. It is conceivable, but not likely, that the only two guys on the 2013 roster would be Lloyd and Slater. I doubt Branch and Stallworth would still be around so the draft and free agency become WR-centric, and Brady would have to adapt to a new set of guys.
The other wrinkle in this is Hernandez. He's a big slot receiver in my estimation. Brady's comfortable with him and he could move into Welker's role.
The Pats have replenished the other major position groups with youth the past three years, so maybe the plan is to focus on WR in 2013. A rookie wideout in the first round is more affordable than ever, and there will always be talented veterans who would love to come and play with Brady, so veteran options will be abundant.