Software decays, some of it faster, some of it slower. Aside decay, we periodically have extinction events, like the switch to the web that killed a lot of thick client software, the shift to mobile, and even the shift to AI. Sometimes it's something mundane like fixing how time is tracked (Y2K) or ASCII->Unicode. To survive, software must have enough developer time to offset the decay and weather the extinction events. Hosted as a Service software has an additional pressure: the cost of hosting and additional maintenance pressure from forced updates. I think a lot of us, and a lot of customers don't really think about decay and extinction events as much as we should.