Echoing what fig96 said, Cruise in fact did not want to market the movie as the "final" anything, but seeing as the last one underperformed (stupidly releasing the weekend before Barbenheimer), and considering how much the budget for this one ballooned, Paramount felt that billing/framing it as an Endgame-like event would guarantee more money at the box office, and it turns out they were right (maybe less so creatively, but definitely financially).
In fact, in a recent interview, Angela Bassett revealed that she recorded the voice over for her opening monologue (on the should-you-choose-to-accept-this-mission VHS tape) only two months before the movie's release. Which implies to me that a number of nostalgia elements were tacked on and integrated where they could be, which would also explain why that stuff feels forced and overbearing at times. It sounds like it was a constant push and pull behind the scenes as to how far to take that stuff. Granted, it's obvious that things like Donloe's involvement were planned from the start, and I know Cruise and McQuarrie were planning on taking a break from the franchise after this regardless, but ultimately I think that's all this is - a break.
Cruise is currently shooting an Alejandro Inarritu movie, and then I know he has some other stuff planned as well, some of it with McQuarrie, including the third Top Gun movie. Also, Skydance (who makes all the Mission: Impossible movies) is currently in the process of buying Paramount - the deal is done - but it's taking forever due to the Trump/CBS lawsuit (Paramount owns CBS), which is holding up the finalization. That should be resolved soon-ish, though, and finally close this year, then once the dust has settled, Skydance will no doubt want to talk/figure out the future of the franchise with Cruise & co.
If I had to guess, Cruise finally hands the baton off to a Glenn Powell type, but continues starring in the movies as more of a mentor/instructor/administrative type, who gets pulled into the action in, say, the third act. Something along those lines, where he's not destroying his body in his late 60s via multiple stunts in the same movie, but still participates in some capacity in a stunt each movie. Ultimately, though, who knows.
But no, this is not the official end by any means. I just think it's the end of this particular crew (Luthor, Benji, etc), and Ethan Hunt driving the action for the entire runtime. I'd bet anything the franchise revs up again, circa 2029/2030 or so, with somewhat of a "new class" vibe, but Cruise still involved/participating (and definitely calling the shots behind the scenes).
