The word comes from “multiple sources with knowledge of Blizzard internal plans” (or, as Google Translate puts it, “the plurality of source familiar with the internal news Blizzard”) who say the HD remake will offer the same gameplay as the original release, but will boast updated graphics and an improved interface. Details will be revealed in November at BlizzCon, according to the report, but the initial announcement is a good fit for next month because it will presumably coincide with the final StarCraft 2 World Championship Series Circuit Event for 2016.
It's pretty thin, as rumors so often are, but it does dovetail rather nicely with the news from late last year that Blizzard was looking for a senior software engineer to work on its “classic games.” StarCraft is now 18 years old (and StarCraft 2: Wings of Liberty is hardly a newcomer either), yet the franchise remains immensely popular. An HD remake, especially now that esports are a wee little bit more popular than they were when StarCraft was new, makes a lot of sense.
Unfortunately, Blizzard is keeping mum for now: In response to my inquiries, a rep said only, “We don't have any announcements to make at this time.”