> And there are many things one junior could be helpful with that a different junior would be useless at.
That maybbe true, and would be an interesting topic do discuss if people actually spoke in such a way.
"Developers are now more productive in a way that many projects may need less developers to keep up productivity levels" is not that catchy to generate hype however.
However, the expansion in scope that senior developers can tackle now will take away work that would ordinarily be given to juniors.