”While this new Diablo project intrigued Blizzard executives — the basic idea of descending a dungeon to hit skeletons and demons had its appeal — they suggested one significant alteration. Bolstered by the reception to Warcraft, Blizzard advised changing Diablo’s combat system from a turn-based one to a real-time one. Funnily enough, Condor co-founder Max Schaefer admitted to Gamespot that the developer initially resisted the suggestion. ”We fought that transition for a long time [...] The amount of time we argued about it was totally ridiculous, considering it only took us about three hours to mock the game up in real time,” Schaefer stated. He elaborated how a realtime combat system would make Diablo feel too much like an action game, but he concluded, ”once we started to play in real-time, it became very apparent we were wrong.[...] We just played it in real time and said, ‘OK, right then, this is how it’s going to work.’”
Doubt it would change. Due to Blizzard's focused and time consuming development philosophy, they've innovated in the RTS, ARPG and MMORPG genres, and still display the highest sales in each of these categories. Hope they continue doing so.