David Kim was speaking at gamescom 2012 and mention that if new units are causing balancing issues and they could be cut. Now this a thing I don't understand. If an unit is causing trouble, then why not balance it instead of getting rid of this unit. “We are definitely open to cutting units,” asserts Kim. But as we all know there's always someone that is gonna cry if something is taken out of a game, even if it isn't a feature they use.
He also stated that the Heart of the Swarm beta will run as long a as it takes to get the game were it needs to be. So if you're looking for a release date and you need to look elsewhere, or is this a HALF-LIFE 3 release date.
SOURCE: http://www.vg247.com/2012/08/17/blizzard-we-are-definitely-open-to-cutting-units-in-starcraft-ii/