TL;DR: Verstappen won't be donning a Mercedes or Ferrari F1 suit before 2026 + given his twenty something age, he can afford a WDC title hiatus in 2024 and 2025.
Don't believe the hype and spinning. Verstappen will remain at RBR in 2025. Toto Wolff had him on his radar for 2025 for the seat vacated by Hamilton, talks were held this Summer but no deal materialized. Moving on, business as usual.
2026 introducing new regulations and RBR cars no longer sporting Honda engines, may be a different story. If Verstappen is not satisfied about the new car and engine and if Mercedes or Ferrari offer him a seat, he will be at Mercedes or Ferrari in 2026.
Not winning the WDC title this year and in 2025 should be no major obstacle for Verstappen.
Compare with Hamilton: Hamilton got his first WDC title in 2008 (P1 - McLaren) at the age of 23. Subsequently, a 5-year WDC title hiatus, without podium in the final WDC title standings: he ended P4 and P5 the next five seasons after his 2008 WDC title (2009: P5 (McLaren) | 2010: P4 (McLaren) | 2011: P5 (McLaren) | 2012: P4 (McLaren) and 2013 P4 (Mercedes)). He got his second WDC title in 2014 (P1 - Mercedes) at the age of 29 racing the Mercedes rocket that would dominate F1 for years on end from 2014 onwards.
Verstappen is currently 26 and already got 3 WDC titles (2021 - 2022 - 2023). His chances for a 4th WDC title this year are threatened by the improved McLaren cars, but mathematically it's definitely still possible (62 WDC points lead). 8 GP races, 3 Sprint races (Austin, São Paolo and Lusail) and 8 Fastest Lap points are up for grabs. Any 'no points' GP finish for either Norris or Verstappen could be crucial.
Verstappen has time on his side and, although always determined to win, he can handle a possible 2024 and 2025 WDC title hiatus. But I trust that he definitely wants to be back on WDC title track course in 2026 with either RBR, Mercedes or Ferrari.
I can see him racing in other car series by his mid thirties. And for sure someday he will compete at the 24 Hours of Le Mans endurance race, maybe with Nyck de Vries as team mate (Helmut Marko won it in 1971 with a Martini-Porsche 917K - he will also give a shot at it).
It's not only all about the car you have - also what you can do with it matters. Of the whole F1 grid, Hamilton and Verstappen have the best skills to make optimal use of the cars they're given (both in terms of set-up and racing). Get them a slow horse and they may still win against a fast horse with a lesser skilled rider. Get them a donkey and they are no competition for a fast horse with a lesser skilled rider.