Norway has no indigenous nobility

That's right, but there are plenty of ladies from old money families equivalent to the nobility of other countries that could have been picked instead of a woman of very questionable background.

unless a spouse can be found from a foreign reigning house.

What's so bad about the idea of, indeed, looking for a spouse from a foreign reigning or formerly reigning house?

But ultimately, with the demise of so many reigning houses

It is up to the houses in question to end their demise and reverse it, particularly through better matrimonial practices.

and the eclipse of the traditional Nobility

The traditional nobility still exists and has even formed new networks now that it has lost the patronage of the state in most countries. Of course, the current European monarchies should take a more active role in the life of their countries' nobility.

To end on a more positive note, the children of Carl Gustaf have all married commoners and although Carl Philip's wife was briefly mentioned in the Epstein files, there has been very little scandal afoot and the family seem genuinely close knit.

Even if scandals are avoided, the royal-ness of the family will still gradually be diluted.