Ubuntu to halve support length for non-LTS releases (The H)

Yes, that's what MATE does. (Its Nautilus fork is installed as /usr/bin/caja)

Distros should do it by providing two binaries ('nautilus' and 'nautilus3').

Another alternative (used in Windows and Mac OS) is to install another Nautilus in a separate directory, but for whatever reason it's not widely used on Linux-based systems.

You need to change binary names, library versions, and maybe a few other pathes, so I'd advise doing it in collaboration with downstreams. It is entirely doable though, but a little more (and quite boring) work.

We did this with KDE3 and KDE4, and many users were understandably rather thankful for that. :)

Still, users depend entirely on what downstreams *want* to offer, for example some distros (hi Fedora!) didn't ship KDE3, even when it was entirely possible from our POV. That didn't make us many friends from those camps.

> Wouldn't that require 2 different Gnome stacks ? How would a distribution handle binaries (ie would /usr/bin/nautilus be the gnome3 version or the gnome2 one) ?

Basically, yes.

This was the biggest mistake Gnome devs made. They did a good job of ensuring backwards compatibility for applications by supporting parallel GTK2 and stuff like that, but they didn't allow for user backward compatibility. They had reasons for wanting it done this way, unfortunately users are more important if you want to make sure that they are taken care of.

This forced people to make projects like Mate to fill in the gaps.