Blizzard Entertainment has stated that there will indeed by at least six new releases by them within the next three years, all of which will be from proven franchises. Note however that they use the word "releases" and not "titles" or "games". In no particular order, five of these releases will be expansion packs, two for World of Warcraft which will be coming up on it's 10th birthday by that 3rd year, two for Starcraft II (which everyone knew was coming), one for Diablo III, and then of course the release of Diablo III itself making six total.
Sometimes it's easy to think of Blizzard as a company that has it easy... a fat cat hotshot that can just sit back and get rich of the massively popular World of Warcraft, but actuality I think this shows just how hard Blizzard works. None of these games/expansions are small releases, each one is huge and on top of that, each has a very large online player base and community which requires constant tweaking and balancing as all online games usually do. It's as if Blizzard is running three different marathons at the same time and staying in the lead in each with no signs of fatigue. Pretty impressive if you ask me and undoubtedly one of the reasons Blizzard games are so well respected... well.. that and the fact that the games are just plain awesome fun