Eight years ago, Microsoft ceased support for Wnidows XP, and the support for Vista was terminated in 2012
Blizzard will follow in Microsoft's footsteps later this year as they slowly stop supporting their games on WinXP and Vista OS.
"Starting later this year, we will begin the process of ending support for Windows XP and Windows Vista in World of Warcraft, StarCraft II, Diablo III, Hearthstone, and Heroes of the Storm. Microsoft ceased mainstream support for these versions of Windows in 2009 and 2012, respectively, but since a decent portion of our audience was still using them at the time, we continued supporting them. However, there have been three major Windows releases since Vista, and at this point, the vast majority of our audience has upgraded to one of the newer versions." said a forum post by the community manager Ornyx.
The only reason the support on these systems lasted into 2017 is the fact that many people who play Blizzard's most popular games, ran them on XP OR Vista, but have now upgraded to at least Windows 7. Now, the support for Blizzard's most famous games: World of Warcraft, StarCraft II, Diablo III, Hearthstone, and Heroes of the Storm, will stop at a "staggered schedule".