Just a quickie: during a panel at the Valencia eSports Congress (reported by PCGamesN), Starcraft 2 design lead Dustin Browder stated that Blizzard are "looking at free to play as an option for the multiplayer." However, getting the monetization balance right could be an issue.
"We don't know how we would monetise it," he elaborated. "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 2 (and its predecessor, notably) is a legitimate eSport, but its competitors such as League Of Legends and DotA 2 are either free to play or relatively inexpensive; allowing them to reach a wider audience. Would you get involved if Starcraft 2's multiplayer went freemium?