Re: Does this mean there can now never be a USB-D?
"It took the EU over a decade of quibbling to approve this mandate. "
This is misrepresenting the facts to some degree.
A decade ago the EU gave the manufacturers the chance to sort the standard out themselves. (Note the mention of a "moratorium of understanding" in the article.) Only after it became clear that that wouldn't work (mostly because of one company using a fruit as their logo and name) did they start the process of implementing regulation. This took a few years, sure, but not a decade.
Also, the regulation contains language that allows for a review of the relevant standard without going through the full process again.
So yes, switching from USB-C to a yet to be designed new standard will be a lot faster than you expect.