I'm a bit worried if we should really go down that path.

Not because I have issues with GPL2+ (I'm usually happy with
everything that makes licensing more flexible), but because I'm worried
we're creating a legal minefield.

Think about this: You may ask me if you can relicense all the ebuilds
I've ever written as GPL2+. I'll say yes. Though ask me if you can
relicense all the ebuilds I've ever committed? Well... They came from
bug reports, overlays, heavily edited by other people, and I have no way
of tracking that. I added them under the implicit assumption that
someone who has submitted such an ebuild to bugzilla or to an overlay
with the gentoo/gpl2 copyright line in it would implicitly agree that
they would be redistributed under those conditions. IANAL, but I think
that's a fair assumption. But do all these people that created or
contributed to the ebuilds I ever committed agree to a
GPL2+-relicensing? No idea, probably not. Is their work relevant enough
to have a license at all? IANAL.

*If* Gentoo decides to go this relicensing way I'd recommend to only do
that if it's coordinated with organizations that have deep legal
knowledge of these issues (e.g. like software freedom conservancy) and
if some lawyers that know this stuff well approve the plan.

-- 
Hanno Böck
https://hboeck.de/