a) slowly lose to competitors as you can't keep up with increased demands in the space. b) take on more and more existential risks

For a lot of companies, that is exactly what they want to do. Its called the exploit phase, I forgot what business lingo this came from. Do a practical feature freeze, cut costs to the max, and squeeze all the value out the product for as long as it lives. Informally known as enshittification. Its all about cost-cutting rather than market capture.

You can last a while though, especially because there aren't many changes so there's also less operational risk.