There's still a lot of speculation on possible candidates and not a lack of clarity, but:
Opposition: Carlos Mesa is running again, as is evangelical pastor Chi Hyun Chung (he does need to find a running mate though). Camacho seems like a sure bet to enter the race, possibly with fellow protest leader Marco Pumari as his VP.
MAS: Still in the early stage of speculation, most rumours point towards Cocalero leader Andrónico Rodriguez and former President of the Senate Adriana Salvatierra as possible heirs to Morales, which is fascinating considering both are only 30 years old. There's some talk about some of Morales's former ministers, but it doesn't seem that relevant at the moment.
The Camacho-Pumari alliance has collapsed, due to Camacho’s leaking an audio in which Pumari requests $250,000 (supposedly to finance the campaign) and control of some customs offices. Pumari will run on his own. I saw a list going around for MAS with Rodríguez, Salvatierra, and a scattering of Evo ministers (Luis Arce?) I don’t remember, but Rodríguez seems like the frontrunner.