I've always been a Welker guy, usually owning him in multiple leagues, and typically targeting him as a solid value pick in most drafts. This year, I think I'm more hesitant than I've ever been in the past, for a couple of reasons. The biggest thing, for me, is his age/health, and how that factors in with how he's used as a weapon. Welker's bread and butter has been doing a lot of the "dirty work"... i.e. catching short/quick passes over the middle. Keeping that in mind, it's not a surprise that he missed 3 games last year. Heck, it might even be a miracle that he played in as many as he did... Not just last year, but over the course of the last half-dozen seasons. He's been extremely durable, which is one of the reasons that he's been one of my favorite players to watch, over the years. Just an all-around tough guy. If John Madden still did his all tough-guy team (or whatever it was called), Welker would be a perennial member.
So, health/age/durability is a concern. Sooner or later, being a tough guy in the NFL seems to catch up with you. In other words, in my mind, it's not a matter of if Welker misses time this year, it's when. He's going to once again do a lot of the dirty work, and he'll take his share of shots as a result. That doesn't mean I'll shy away from him, but I have to somewhat temper expectations. I no longer view him as a low WR1 or high WR2 (in standard sized leagues). I think he's a WR2 in deep leagues, and I'd be thrilled to have him as my WR3, but I don't think I could live with him as my top guy, and if he's my #2, I'd better have some depth behind him. Not because he can't end up with 90/1000/10, but because the risk is there.
Add in the fact that they added Latimer, and I'm concerned just enough that I'm going to think twice before drafting Welker. I'll probably still pick the guy, if he's there at a point where I think there's value, but the risk is there. He's bound to have another concussion (or knee injury, etc.), sooner or later. In dynasty leagues, I wouldn't say that I'm actively shopping Welker, but I'm less inclined to hold him. If I can get some value for him now, it might be the prudent move.
On the other hand, Sanders is no Eric Decker. Sanders didn't do squat in Pittsburgh, and if he puts up numbers this year, it will be because of one thing... Peyton Manning. Decker, on the other hand, is a stud, and he'll (once again) prove it this year, when he has a lesser QB (and no supporting cast). So, in that sense, yeah... Welker's targets may not decrease all that much. I'm more concerned that he stays on the field, than I am with others eating into his playing time and/or targets. When healthy, Welker will be on the field (and Peyton will throw to him).