A tall player who can't make threes, is more limited in the modern NBA and more limiting for roster construction. As a result, a lot more practice would be allocated to shooting from range. Look at someone like Brook Lopez (7-foot centre) who attempted 31 threes total in his first 8 seasons. Then started attempting 250-500 threes/season after that (peaked at 512 attempts).
Developing players who are elite prospects are also now less likely to be pigeon-holed during development into: you're tall as a 12 year old, so just focus on drills for centres. So yes, there would absolutely be growth in the number of capable shooters.
On your point about realisation, teams already optimise to favour threes and high-percentage twos. They try to stretch defence to each extreme, but you need to excel and threaten at both things at any given point because teams will adjust constantly during the game.
Developing players who are elite prospects are also now less likely to be pigeon-holed during development into: you're tall as a 12 year old, so just focus on drills for centres. So yes, there would absolutely be growth in the number of capable shooters.
On your point about realisation, teams already optimise to favour threes and high-percentage twos. They try to stretch defence to each extreme, but you need to excel and threaten at both things at any given point because teams will adjust constantly during the game.