Blizzard recently let loose the information on the units they were adding to Starcraft 2: Heart of the Swarm. Blizzard is adding a few units to each race and also removing units as well. Expansions typically add to the mix, they don't remove. That said, it will give people a reason to return to the Wings of Liberty game. I wonder if different events will have Heart of the Swarm tournaments as well as Wings of Liberty? I wonder how the games will differ in balancing? Oh well, interesting to say the least.

A few units getting the cut in Heart of the Swarm:

"In the current design of Heart of the Swarm, the protoss are not able to deploy Motherships and Carriers, though these and other units that don’t exist in Heart of the Swarm multiplayer will still be available in Wings of Liberty multiplayer and the solo campaign."

Units that will be revised:

"In Heart of the Swarm multiplayer, terran players will be limited to having only one Thor at a time, but this new behemoth hits even harder with its regular ground weapons and can absorb a tremendous amount of damage. The terrans have also swapped out the Thor’s anti-air weapons for a bombardment ability that does a huge amount of damage to a wide swath of ground. The Thor will need time to set up its bombardment cannons, as well as time to repack them after an attack, much like a Siege Tank. Of course, fielding such a powerful weapon requires a hefty investment in technology, so both an Armory and a Fusion Core will be required before a Thor can be built."

Be interesting to see a full list on Blizzards site before launch about all the changes.

If you are interested in seeing how a Heart of the Swarm match plays out check this recent Blizz battle report: