I'm not a Chiefs fan but I think you are undervaluing the fact that this franchise is pretty well run.
We've seen firsthand over a 20-year period how good coaching and a great QB can make up for a lot of deficiencies in both personnel and talent. It was never the Chiefs plan to have Hopkins and Smith-Shuster be focal points in the passing game for the long or short term. The Rice injury I think put a dent in their plans.
This was not a great season for the Chiefs despite their record, and the Eagles exposed some major deficiencies in the O-line, which I expect the Chiefs will prioritize this offseason. I'm not sure what Rice's timetable to return is (he has some legal issues to work out as well IIRC), but if he comes back healthy and Worthy doesn't have a sophomore slump that's a pretty decent top two targets. If they can fix the line and give Mahomes time, I expect him to at least return to top 7 QB status (which he was nowhere near this season).
I agree Kelce is getting long in the tooth, but he has been faltering the last couple of seasons (including last year when they won the SB). His current production while still good won't be nearly as difficult to replace as it was a few years ago.
As for the defense, despite looking bad in the SB, they still have a very good coach who will maximize guys and put them in position to make plays, much like BB often did for the Pats, often with guys no one else wanted.
Does this all translate to a Chiefs dynasty that will match the Pats? No way in hell. I just don't think anything like that will ever happen again. But I don't think they're as dead in the water as some are saying.