First off, I am not sure we need to improve on it in the short term. USB-A has existed for ~20y by now on the desktop and is still going strong. If USB-C lives as long, we'll get a break from having to buy different cables for quite some time, which at least is great for /my/ nerves. When I threw away old phone chargers from 1996 and later, it was literally 10 different models.

And if USB-C doesn't cut it anymore, who's to say that industry can't move to a different system? EU legislation usually isn't outlandish but follows industry practices. If device manufacturers bring up a pressing need for USB-D, EU will allow both for a transition period and then mandate USB-D (or split up mandatory standards by device class if need be).

I don't see how every tiny iteration of a standard has to result in a different plug system - the incentive for companies to iterate plugs just to force consumers to re-buy gear is just too high.

See other thread. If the industry wants it, it is highly effective in influencing legislators. It is called lobbyism and typically we complain about it but sometimes it is also good.

Why do you think it can't be changed to something else in the future?