It would be nice if portage could safely migrate back to prvious releases. Such as when you're returning back to gnome 1.4 from gnome 2.0.
You mean like an "undo" command?
I wrote this a long time ago, and I'm not quite sure what I was thinking of (evidently I was thinking of moving back to gnome 1.4). However, it's probably possible to do what I was thinking of. But I thought about it some more, and what would really be nice is to be able to unmerge a package AND it's dependancies, without unmerging other package's dependancies (to a point, like not keeping Gnome just because Mozilla needs it when what you're trying to do is unmerge gnome in the first place). However, it's my gut instict that you can do this already. I just haven't had the time, energy, or real need to figure out how. Maybe a Gentoo How-to guide here? However, while I wasn't originally thinking of UNDO, it might not be a bad idea.
Don't think this'll happen and if it does, it's a portage-ng thing.