I do wonder what the bike industry might have to say about that. Some companies might welcome the dramatic reduction in R&D costs, specific tooling etc needed to make TT bikes plus they’re not exactly big sellers in the mass market.
On the other hand, it’s not so much the fact that TT bikes (in and of themselves) are dangerous, it’s the fact that riders are going out on open roads in super-aggressive aero positions and they have limited visibility and control. It’s one thing doing that on closed roads with support cars, barriers, a DS giving instructions in your ear, it’s quite another doing it on an open road with random traffic.
You could maybe get the UCI to add a few extra paragraphs to the already insanely complicated rules around TT positions – which could then lead to the question of why use TT bikes anyway if they’re going to be made more like road bikes.
It’d be difficult to mandate riders to using them indoors or under closed conditions only although it wouldn’t be unreasonable to recommend training indoors / on a velodrome to get the position sorted and then ask teams to arrange training sessions at motor-racing circuits to practice outdoors / in real weather. But the riders do need to ride the bikes a lot to hone the position and the technique so it’s not wholly practical.