Manufacturers (should) know how well they designed and built their boards.Tested does not mean validated. The AMD reps quoted in the Toms article have no idea what they're talking about.
Part of the qualification is proof by design, and by definition no PCIe 3.0 mobo is going to meet the 4.0 design requirements.
This stuff is way way waayyy more complex than average joe realises.
If it was designed for just passing minimums, there's certainly no hope, but if design was for high quality...
And if not possible at all, why manufacturers even had PCIe v4 in those available for public Ryzen 3000 support beta BIOSes?
They would have kept it in internal testing if chance for working was small.
Common sense should tell that.
Or I guess neither mobo makers have any idea of what they're doing...