Sur'Kesh would be the most ideal location for a Jungle Map, IMO.. Though, if they pulled it from the campaign, it would end up being the science facility that you go to get Eve from.
Thessia's place is more than likely a modified Temple area. Firebase Goddess? Religious ties, plus that being the main area you went to in the Campaign.. It's a pretty decent bet.
Railway?.. I didn't see that in the OP, but that would be interesting to see, I suppose. Saw a 'string' of some sort, from another thread.
Firebase London and Firebase Vancouver would be perfect additions to the game. I enjoyed playing in London, in SP.. and Vancouver was bright and cheery, while London was dark and heavy. Perfect set up!
As for Vorcha.. I honestly wasn't a big fan of them, so.. Cool and all, but just like the Batarians, I don't really care for them.
The Phoenix characters are more than likely Prothean though. I'd love to see Prothean MP characters. Though, I'd prefer a Sentinel or Solider over a Vanguard. Adept would be awesome though! Slam, Dark Channel and Singularity would be a good combo for Adept powers, maybe?
As for the Quarian thing, I honestly hope they put Turians instead. A Turian Infiltrator, and a Turian Engineer would be badass!.. or at least the Infiltrator.
Either way, if this is true, I can't wait to see it!
Other additions that would be neat to see is Mercenary enemies, similar to Pirates/Krogan Mercenaries from ME1, and to see some other locales, like the Grissom Academy as a Firebase, or a map like the one in the Tuchanka: Bomb mission.