Tbh, I'd trade 3.0 boomerang for better mobility and faster speed overall. If they want to "fix" Link, make him a "real" character. Give him a better wavedash (less friction and less startup frames on jump animation), better dash dance (faster and longer dash), just better fundamentals for the character overall, so that the player can be more rewarded for their fundamental skills. I'll admit, Link can be easy-mode, autopilot, and he doesn't have to move much to combo, lol.
On the other hand, if they just nerf boomerang (especially as a KO setup), that's gonna be a big deal, as that's taking away a reliable KO option (his best one at that). Boomerang pretty much covers how slow Link is, and with the nerf, it's going be easier to get in on Link and pressure him. So yeah, Link's design overall is decent, but his attributes (overall range increase and boomerang properties) are great. As the metagame progresses, I think Link actually gets worse as more players figure out ways around Link's tools. It would only be a matter of time. Link reminds me of Snake in Brawl: great at the start of the metagame, but gets progressively worse when players learn to exploit his glaring weaknesses.
/my2rupees