well, as far as it being possible, it's possible
the first thing that would hold me back is finishing/adding a lot of concept/unfinished w.i.p. (work in progress) stuff that i really wanted to include in outbreak, such as a long range "sniper-like" weapon (something like a energy rail-gun with zoom/scope), a fresh (and proper) recompile of the buggy, a few sound tweaks and a handful of other stuff
it would be hard to jump into ep1 with certain stuff still floating in the air, however i'm sure many people use their own weapons or custom addons, so really it comes down to the time of cooking up the mapadds, and lots of debugging/work-arounds to ensure the campaign is fully playable with the least amount of "game-breaking" events
ive only tried running it in ep1 a handful of times, and while it functioned somewhat properly, there is far too much play testing that would be required which i doubt there is enough interest for (as a whole) to meet debug needs
i dont know, pretty doubtful, but as guard said..who knows what the future holds