it wouldn't take much to get on the same page, maybe companies all ready are more or less there. As was mentioned, all that really has to happen is a couple major players to get together, agree to a couple sizes, call it something and run with it.
Many companies won't want to do some of it if it means they are the one that has to change. The compromise could be pick sizes that no one uses so everyone has to change.
Many tools have replaceable ports, so updates could be done (Festool did this on the track saws). And of course there would be an adapter industry. But if it basically means companies like Festool need to make and sell 3 sizes of adapters from their ports to the standard ports, it's not a big deal. Apple loves to make Dongles
I think when you look at the companies out of the EU a lot of it is fairly standard. I think the issue is the US hasn't had dust collection, or real efforts on this till lately, and is stuck in inches, and thinks "shop vac" as standard. You will have companies that refuse to accept the metric system and thus refuse to make "mm ports"