Disney are yet to incorporate the Fantastic Fours and the X-Men into the MCU + they have not really expended the Star Wars universe yet.
They have a multi-channel approach and films are just one of the channels.
Disney will be fine for a VERY VERY VERY long time without having to add more IPs... and they surely will.
What many people fail to realize is that, for Disney, it is not about films it is about creating brands. Brands that they can leverage as films, shows, comic books, video games, toys, etc. Hell, licensing is probably more profitable than movies for them.
In other words, they don't care about nerds complaining about their movies as long as little girls ask Mom and Dad for a Rey costume for Halloween, a Captain Marvel doll for Christmas and Disney+ to watch Frozen. In business terms; customer lifetime value.