[eggpy]

You tell your boss(es) about your concerns and onboard some new people, and you do something new. Either within the company; find a team that needs people or try to pioneer a new app, or change companies. Or accept being the expert and enjoy a promotion!

[maxxxxx]

I don't know where you work and what area but this seems a little optimistic.

[eggpy]

I've worked at a few places of vastly different sizes. From a company with only three devs, an office with three hundred devs, and a fortune 500 with over 3000 devs (not necessarily in that order). Maybe I've just been lucky, but at all of those places I've had conversations with my managers along the lines of "team x is doing something I find interesting and eventually I would like to do that, can you help me get there?" or "I have an idea for a project x that would be useful to us, can I block some hours to work on that?". Generally they have been amenable, and if not then I've moved companies. You need to be responsible for your own career, and I like working at places that encourage personal development :)

[maxxxxx]

This used to work for me until around senior level but after moving up a little more (with corresponding salary) I find it harder to move around while keeping the salary.

[Skunkleton]

I think that you probably would have to be OK with a pay cut.

[maxxxxx]

That may explain why a lot of people stay put once they have achieved a certain level.