This evolution comes at a cost - if one senior suddenly can do their work and plus work of 5 juniors - why would company keep these juniors? It won't - the moment C-suite realizes they don't need extra people, they will be gone. But at some point senior engineers will retire or find new better paying jobs and said company would need to find a replacement. In the past this replacement could come from one of the juniors that worked in that company for a while and mentored by the senior. Not so much when there's no more juniors thanks to AI.
Not so much evolution here, I'm afraid. Just a plain redistribution of wealth upwards thanks to new tools that made large chunk of workforce obsolete. How this will affect industry in 15 years - nobody seem to think about that.