Blizzard is essentially the gold standard when it comes to post-release support. Heck, the most recent patch for Diablo 2 — originally launched in 2000 — came out earlier this year. 2010's StarCraft 2 is no exception, with Blizzard preparing a significant "revamp" to the game's multiplayer.
You'd expected a patch for a six-year old game to exclusively deal with compatibility, stability and bugs. That's not the case with update 3.8 for StarCraft 2. The developer is calling it the "Multiplayer Revamp", reflecting the extensive changes to game, including complete redesigns of some units.
For instance, the Terran's "Cyclone" is being transformed into a purely ground attack unit that will be tougher, cost less and have fewer tech requirements. For the Zerg, the Hydralisk is "being transformed into a core tech option". To this end, it'll receive two new upgrades — derived from (and replacing) "Muscular Augments" — which will beef up its movement speed and attack range.
Protoss will also receive attention, though not to the same degree as the other sides. While the Tempest air unit is getting a new stun ability, its role won't change significantly. However, the carrier's interceptors will become entirely automated, with the release option removed and construction auto-cast by default.
According to the announcement, the major update will make way for smaller "less disruptive" changes in the future. You can see the full details over on Battle.net.
Patch 3.8 Preview: Major Patch for Multiplayer [Battle.net]