Im guessing that when it is ported, they port anything in the mozilla code base the phoenix uses... This would include the new toolkit (the XPFE successor), which will also be used by thunderbird and prolly many applications. The thing is, their going to be be porting a lot of mozilla, so why not just finish it off. Just the main parts that allow us to run other moz apps.
I tend to think whats better long term, and thats what i think. Plus

i dont share your despiration to get a new browser, as i use firebird on windows

...
But ill maintain, that, maybe if they could get firebird working first, and then concentrate on the rest of mozilla so that one can run the new mail client, the jabbaclients the games and everything else...
either way, its gota happen. Mozilla could end up toppling GNOME, KDE and Enlightenment... (eventually)