It was always going to be the end of an era as the actors and actresses contracts end and they need replaced. Saw th movie have left my view in other postings (13)...
The issue as have always seen it is Captai Marvel just isn’t an interesting character. Never has been in the comics, no matter how much girl power and forcing it on the public marvel has done with her, she’s just bland always has been.
Trading Iron Man as the main character in MCU for Captain marvel was always going to be a step down, wokeness or not
Other than RDJ, I think other actors could step in. I was more along the lines of the era of just fun MCU movies. Homecoming with the annoying MJ character was the first warning sign.
Not sure when CM was tagged as the future. Did that pop up just within the last year? If CM is a hero with no weakness what drama is left for the MCU? Honestly Black Panther would be a better leader of the next stage of the MCU.