It's a flavour of Jevons paradox. Make production of software much more efficient (requiring fewer developer-hours), then you might get:

1. Same services provided using similar software stack, but maintained by fewer developers. I suspect this may hold for some sectors in the economy. Or

2. The Jevons case: similar # of developers maintaining a much bigger software stack that provides more services.

I might add:

2a: Similar but with lots of accidental complexity everywhere.

Probably we're heading towards some mix of the above? Depending on which application area you're talking about. Web dev is a lost cause, deeply-embedded won't see a big shake-up.