Blizzard could very well announce an HD remaster of StarCraft next month, if reports from iNews24, a reputable Korean news source, are correct. iNews24 says multiple sources with access to Blizzard's inside plans suggest that the company will reveal a StarCraft HD remake some time in September.
As Kotaku pointed out, the StarCraft II World Championship Series holds its finals from September 10 to 11 in Mexico, making it an ideal time for a new StarCraft announcement. iNews24 expects Blizzard would then follow up with additional information at BlizzCon in November.
The Korean report also suggests that the remake will maintain the original gameplay while giving the graphics and user interface a boost. That's about all we have to go on at the moment, and it's worth remembering that this is pure speculation for now, unless Blizzard releases a statement.
StarCraft was originally released in 1998. Although it's showing its age as far as graphics are concerned, the game still draws quite an audience. It makes its home in the top ten Korean net cafe rankings, currently sitting pretty at number seven. It keeps good company with newer games like Overwatch and League of Legends (numbers one and two respectively).