I think that software development is just an extremely poor market segment for these kinds of tools - we've already got mountains of productivity tools that minimize how much time we need to spend doing the silly rote programming stuff - most of software development is problem solving.
Given the growth-oriented capitalist society we live in in the west, I'm not all that worried about senior and super-senior engineers being fired. I think a much more likely outcome is that if a business does figure out a good way to turn an LLM into a force-multiplier for senior engineers, they're going to use that to grow faster.
There is a large untapped niche too that this could potentially unlock: projects that aren't currently economically viable due to the current cost of development. I've done a few of these on a volunteer basis for non-profits but can't do it all the time due to time/financial constraints. If LLM tech actually makes me 5x more productive on simple stuff (most of these projects are simple) then it could get viable to start knocking those out more often.