During a panel interview at the Valencia eSports Congress, Blizzard's Dustin Browder admitted that the company are considering free to play as an option for Starcraft II's multiplayer.
The report on Pcgamesn states that Browder, the lead designer on Starcraft II, admitted that Blizzard are "looking at free to play as an option for the multiplayer," when questioned.
The only stumbling block appears to be just how the studio would monetise the shift to free to play: "We don't know how we would monetise it. While it might be good fun for me to play against someone with only half the units available to them, that's not going to be an enjoyable experience for them."
Starcraft II: Heart of the Swarm has just entered into closed beta phase, and so it's unlikely that any sweeping changes will be implemented any time soon, but the fact the Blizzard are considering a shift is potentially huge for the world of eSports.