I'm not going into the Seymour thing again. I find that the arguments justifying the move are not persuasive, and I'll leave it at that.
I'd say that the Brady robot is more what BB considers a perfect representative of the Patriots than the more playful Welker, but that's just a small thing.
Numbers for offenses in general tailed off over the course of the season, and the Patriots were clearly exploiting matchup weaknesses (teams played in the second half included Chiefs/Eagles/Giants/Redskins/Broncos/Dolphins/Jets, which were generally much better on the corners than at safety) so I don't see this as an issue. As for the new players coming in, there's still just going to be one football, and all the new players should also mean that Gronk's numbers take a dip, too. Using the logic being tossed around in this thread, that should mean that Gronk's fit to be traded or at least given a low-ball contract offer.
Gronk had 90 catches and Hernandez had 79. That's 169 catches from the tight ends. Branch, a player that some seem to forget played for the Patriots last year, had 51 catches as the 'other' starting receiver. Now, it's quite possible that we'll see a 20+ reception dip in Welker's numbers and a 20 reception uptick in the Branch position numbers, but Lloyd's career high is 77 catches, so that would be closing in on that mark. It's also quite possible that we'll see a 20 reception dip in Gronk's numbers, or a 10-20 reception dip in Hernandez numbers. The approach the team will take seems likely to be similar to 2007, where the Patriots were tossing out a 5-man 'receiving' group of Welker, Moss, Stallworth, Gaffney and Watson, and still getting Faulk 47 receptions. Even in that season, though, Welker had 112 catches, so making the equation of "More options = Welker's much less useful" has no basis in the history of the Patriots with Welker on the team. If the team started throwing the ball around enough that Welker ended up in the 90-100 catch range, he'd still be worth a very nice contract.
It's not unreasonable to say that the Patriots offense could benefit from any number of things, including throwing the ball to Welker more/less/same.
That makes no sense to me, at all. The offense put up historic numbers on the back of that "too much".
The offense could improve in many different ways. The problem with your argument is that you're taking a personal preference and acting as if it's significant. It's not. The Patriots offense was so good that it carried the team to the Super Bowl. It was limited in its ability to stretch the field middle-deep, and that's been dealt with. This need for "improvement" elsewhere in the passing game is mythical. People seem to be confusing "would be nice" with "really needed".
Given that he's been setting and shattering records in the past 5 years, that's a safe bet, but a meaningless one as well. It's not a stretch to make the same sort of guesses about Brady's next 5 years, either. That doesn't mean you short Brady, or ditch him.
In football, it's generally best to make your best players your priority. In essence, you're trying to make an argument for doing the opposite. I reject that argument.
I expect that he'll get a 3-4 year deal at good/very good, though not elite, money. If the Patriots are stupid enough to let him get away, that'll be on them, and it'll make the offense easier to defend.