> Most software, once mature, is mostly done.

I think this is a dated mindset with AI in the mix. Not only is AI making it easier to do big-bang rewrites which wouldnt have been done before, it is making working on brownfield codebases more feasible. It is lowering the barrier to entry for non-devs to contribute to codebases. Most software did not stagnate because there wasnt a need to grow it more, it stagnated because the friction and/or cost of change hit a critical mass.

I think we are much too early into the "new era" of software to understand what it looks like tomorrow, especially in terms of what we assume to be true today.