couple of feet is not enough. the line needs to move far enough such that vast majority of the players (more than 95%) shoot less than 30% from there. so probably 8 to 10 feet back. absolutely should happen but they will likely do something awesome like shortening quarters to 10 minutes
curry and bol bol are two good candidates. in today’s nba you can’t tell difference between them on the court except for several feet of height difference. but practically same player as they shoot about the same shots