I don't want to start another useless rant here, because I perfectly understand the issue with ABI specific headers.
The problem is: a) if you break a provider on purpose, then you should feel somehow responsible for the consumers and not just dump testing and fixing on your fellow devs b) just test such things in an overlay first and see it explode, then think about it again and ask on dev-ML if other people find it even WORTH the hassle The other thing is: We still have the conflict with eclass-solution vs PM-solution (multilib-portage) and I propose not to convert ANYTHING else until that conflict is solved, even if it means a council vote (that's what I actually think makes sense here). I understand both sides and somehow find it appealing to have a quicker solution, but since this could damage years of work on a portage fork I think we should slow down here.