Yeah, it is. The signs are unmistakable:
1) There's no succession plan for Brady.
Earlier in the season, they thought their QB2 Stidham might have to play, but he flashed so many mistakes they had to bring in Cody Kessler as the No. 3. With Stidham as the starter, they're looking at Giants-like season results that may be inevitable, but I see them paying TB12 to stave that off while they attend to other needs. With Brady, they'll probably continue to be contenders for a playoff spot, but just that isn't enough to sustain a "dynasty."
Brady also knows that his time with the team is short, but for this year they really need him. He and Rivers make about the same, 23M. Expect Brady to demand more and more guaranteed money, and for Brady not to care how it impacts their cap going forward.
2) McDaniels could be leaving.
McDaniels' attempt to inject "the Patriots Way" to the Broncos was an abject failure, with him seen widely as just an unnecessarily authoritarian, and failed, a-hole. And then McDaniels was going to go to the Colts last year, but stood them up at the last minute.
Despite all this, McDaniels has more job offers than ever. The belief now is that the Pats have been more than grooming him as BB's replacement--they've basically promised him the job. BB used to say he'd be retiring about 70, but has now started telling media he sees himself coaching well into his 70s. McD is now seen as having fixed his HR issues from Denver, and he might not want to hang around for another 5 or 10.
3) BB's "merciless" trait of getting rid of players is no longer consistent, and it is no longer as reliable.
BB alone can't get rid of Brady. And Brady will want Edelman. BB let 39 yo Ben Watson hang around at TE, and Watson's now hanging it up. On the WR side, he sent D Thomas to the Jets after getting AB, and the decision to get rid of AB was Kraft's, not his. Even after that disaster, he released Gordon rather than even attempting to trade him or use him as long as he was available.
Nowhere was the failure of BB's quick-fire/musical chairs approach as apparent as with the K position. Once SG went down, Bill went through 4-5 kickers, some of whom he put on PS. They missed one extra point, one FG or did something in practice BB didn't like, and they were gone. What he accomplished with this frenzy was gifting two starter Ks for Atlanta and Dallas who are as good or better than the one he ended up with.
4) Kraft is seen probably more unfavorably than at any point in the dynasty years.
Seth Wickersham said Brady went to Kraft to force the Garropolo trade, which certainly wouldn't have happened without his permission. Kraft's prostitution arrest (and his getting out of it) left everyone with the impression of a billionaire with the audacity to coast in with his Rolls and driver to pay someone a whole $79 to suck him off twice before taking off in his private jet for AFCCG. That's what Robert Kraft will now be remembered for. There's no indication any more than with Jerrah that Robert will officially turn over the reins to his heir. Not this year.
So tl;dr: Not only do the Pats not have the pieces to prolong the dynasty, they no longer have the success they once did with their process. Players, especially those with options, are less likely to put up with how BB acts now that he himself has compromised his pedigree, let alone how Kraft has contaminated his. They are likely to go with the trend, which has been players complaining increasingly publicly, as seen with Ramsey.