The MEA MP Resource Library (updated April 1)

Human Female Soldier/Human Male Soldier(Common), Human Female Vanguard/Human Male Vanguard(Common)
Human Female Engineer/Human Male Engineer(Common), Human Female Adept/Human Male Adept(Common)
Human Female Sentinel/Human Male Sentinel(Common), Human Female Infiltrator/Human Male Infiltrator(Common)
Turian(Male) (?)(Uncommon), Krogan(Male) Vanguard(Uncommon), Krogan(Female) Engineer(Uncommon), Asari (?)(Uncommon)
Salarian (?)(Uncommon), Asari (?)(Uncommon), Krogan(Male) Mercenary(Rare), Turian(Female) (?)(Rare)

Human(Female) Kineticist(Ultra rare), Asari Duelist(Ultra rare)

There are 12 common, 6(known) uncommon, 2(known) rares, and 2(known) ultra rare characters; 13 humman(C/UR), 3 asari(UC/UR, 3 Krogan(UC/R), 2 turians(UC/R), and 1 salarian(UC) making 22 known characters where as ME3MP had 24 on launch. In ME3MP there were 2 of every alien race(Turian, Quarian, Krogan, Asari, Drell, Salarian); so I imagine for the most part every alien race will have an even amount of characters(excluding ultra rares) with at least 2 uncommon and 1 Rare kit. That's 12 kits with 4 races, however this could be a trade off in the sense that while we get more kits per alian race we get less races. With that in mind; the other three races I mentioned could all be part of DLC.
I don't see the Kett being added unless through DLC; if the the geth, cerberus defectors, and awakened collector are any indication then there is a possibility. The Angara may be in the MP at launch since they've been shown to be rather prominent in the game; we've seen a Angara sniper among the raiders in the gameplayer video shown in December, so it's not entirely without reason to see some of them among the Apex teams. As for the Quarians I'm more spilt on whether they'll be in at launch or as part of DLC; the nexus is our most likely place to see Quarians since the Turian Ark(both are a dextro-based species so it makes sense for them to be together) is missing up to a certain part of the game, most likely once you find it; it isn't out of the question to see them in MP since they could be some Quarians on the Nexus. This is mostly speculation and a bit of observation based on the content that's been in MP(generally speacking).