This sort of thing is why I dislike legislation that mandates the use of something very specific. Things change and it is better to create laws that don’t become outdated as fast as tech tends to.
What normally happens in most countries is the law would say something vague like "digital means or devices such as floppy disks or equivalent".
Then the Executive makes and maintains the rules of application of that law according to the Hierarchy of Norms (things probably are organized differently in Common Law countries so I don't know the English term but the principle is the same), which dictates in more detail how the law is to be applied ("please use a web form, or a USB keys for legacy processes").
Sometimes the executive lags behind a bit but typically it's just a ministry making decisions within the margin of the law, so it's not too bad.
The law doesn't even force USBC it just forces whatever the international standards working group recommends, if they change the recommendation it will change the port.
So we're actually having our cake and eating it.
Also stuff like USB 5.0 specifications are designed to work on USBC port so again no actual upgrade will be required.
The EU regulation doesn't say "USB-C", but "industry standard charging port" or something. What's industry standard is an executive decision of the EU commission, unless the USB-IF does something tremendously stupid the commission is just going to rubber-stamp any new standard they come up with.
The EU didn't event want to legislate in the first place and would've preferred for manufacturers to get together and just be sensible, but, well, Apple. The only hold-out.
Luckily usb-c is probably gonna stick around for a while and it's just a form factor. The standard itself has room to grow, and the EU left the rules open to change.
But I understand the concern, legislating tech sucks. On the other hand, when companies care almost exclusively about profit, not customers or the future of our planet, and won't improve things themselves... not a lot of other options.
Mainly due to proprietary hardware+software solutions which cannot be ported now and remaking them with new hardware will require redoing the same processes as before (probably with additional stuff added by later laws) all over again.