The trick is to redesign the bricks for worse tolerances. With 3D printers you can print very nuanced springy elements that are impossible to achieve with injection molding. I got some reasonable bricks years ago on cheap printers with PETG, should work even better now with modern printers and ABS.

Not in terms of people printing lego bricks. But at least as an adult, designing things in Fusion and printing them scratches a similar itch as building lego. And 3d printing is now pretty accessible to the 14+ age group. I doubt this will completely replace legos, or that it's even their biggest threat, but I'd be surprised if it had no impact

It would be interesting if 3D printers could reach this tolerance