That won’t happen anytime soon. All phones use the USB protocol for data transfer regardless of the port and the USB group is committed to using USB-C well into the future. That means that you won’t get a speed boost over USB-C without going outside the protocol (which is insane) and that if you managed to get the USB group to come up a new speed it’s pretty much a guarantee that USB-C will support said speed.

As a sidenote, the “USB group” is a consortium of big companies, not a government body of any type. Pretty much every single big company who could possibly want to come out with a faster single cable data transfer method is in there, and that includes Apple.

Another sidenote, believing that USB-C can harm innovation in the smartphone space by limiting transfer speeds is ridiculous. No phone manufacturer gives two shits about wired transfer speeds, as evidenced by most of them sticking to USB 2 speeds for their devices (again, that includes Apple and their innovative Lightning port).

Finally, and to more directly answer your question, if that fantasy scenario you described were to happen the company responsible could just knock the USB group and EU’s doors and tell them about their fantastic new standard. If it’s actually an upgrade and it’s offered as an open standard they’ll probably just embrace it and update the standards and legislature. The point of the law is to prevent companies from coming out with myriads of shitty proprietary ports and standards, nothing more, nothing less.

And actually finally now, the law doesn’t ban alternate ports, it just requires a USB-C port. If all else fails the oh-so-poor innovation-starved manufacturers could simply stick their magic-fueled ports right beside the USB-C and call it a day.