I definitely agree with you there. I just don't have quite the level of concern as you seem to, that's all.
Like I said, I see the team choosing to swap out Welker for Amendola. He has experience in this system. Our short passing/timing attack will continue to be the bread and butter of this offense, probably just not to the same level--as we need to have some outside success too, and that is where Belichick has seemed to try and address the weaknesses that have plagued the offense in the past couple of seasons.
In a nutshell, I don't see much of a concern with the short passing game. We have Amendola, Edelman, and could even make do with someone of much lesser talent. I feel that the short game is predicated on practice, practice, and more practice...Belichick will make sure that this aspect is well enough off to continue to see success.
So, that switches concerns to the intermediate/outside passing game, which absolutely sucked last year and the statistics back that up. I don't think that there are many groups who could actually do much worse than last season. If you look at the intermediate/deep routes to the L, R, and middle of the field you'll see a completion rate of 25-30% total. Although you may want "other" receivers from other teams at the moment, I don't think the bar could be any lower than last season in this area--and that is exactly why I am not as concerned as you are.
Any way you look at it the offense should continue to produce with a committment to the offensive line/running game, the 2 TE's, improved depth (and maybe even talent) at certain areas, and of course...Tom Brady at QB. On top of that, the defense is almost certainly improved no matter how you slice it. This is definitely a team that should go 11-5 or better, with a playoff berth almost assured. Injuries are really the only concern we should have, and I don't recommend living in the "what if?" world. As a general pessimist and worry wart, I can assure you that it is not a fun place to be.
