News Sony Extends PlayStation 4 Production to Battle PlayStation 5 Shortages

"It is one of the best-selling consoles ever, and there is always crossover between generations," a statement by Sony reads.

The statement is true but only in the context of the pre-PS5 world. Once the PS5 is out there in the wild, the PS4 loses a lot of appeal for buyers. Also the "crossover between generations" is a result of people already having the older generation before the newer one is released, not the other way around.
 
I think this is a good move.
I imagine it's much easier to get the older components made, and hence it won't infringe on PS5 production..
I do think they stopped producing the PS4 Pro way too soon.
 
They should be producing PS4 Pro and not PS4. The move to produce a console that is quite a lot slower than a PS5 is going to make game optimisation a problem for game developers.