I don't know if you're being facetious our not. I agree that that's the current landscape, but it doesn't make any sense! Imagine a great big ship sailing the oceans in ancient times. The crew made the ship sail straight. Now imagine (for argument's sake) the crew could be replaced at will. Preventing any deviation in the course is it's own success. The ship is working as intended and producing value. So to use your questions:

How will you get bonus if you don't do anything different? You won't crash the money-maker.

How will you do anything different if you don't ignore/brush-aside past successes and focus on replacing them with new things? You won't. That discipline is it's own value.

How will you replace them without funding i.e. more budget, more power? Your maintenance budget pales in comparison to the R&D budget, so funding should be a non-issue. You're not asking to recreate the boat, only replace discrete known quantities.

How will you keep moving up if you don't repeat this cycle? Because the momentum was set at ship launch, not at ship improvement.

I honestly don't understand how this all breaks down in modern times once you introduce shareholders. Is it that shareholders literally get spooked by stagnation?