Microsoft watcher Mary Jo Foley claims Windows 8.1 Update 2 is on track to be delivered on August 12, this month's Patch Tuesday. This update will be relatively minor, it won't be big on new features and will primarily feature design changes. Unlike the previous update it isn't a mandatory update for future updates and it will be pushed out as a regular monthly update for Windows 8.1.
Originally, Microsoft planned to make this update much bigger and important but a couple of months ago this plan was scrapped in favor of reintroducing the new Start Menu with Windows "Threshold". Possibly named Windows 9, this new release of Windows is expected to be ready in Spring 2015. Whether there will be a third update to Windows 8.1 remains unclear, some sources believe it's unlikely while others claim it could arrive this Fall.
Perhaps the most interesting snippet from Foley's article is that Microsoft is planning to offer Windows XP, Vista and 7 users a deal that's hard to refuse in order to get them to move to the latest version of Windows once it's out in 2015:
Microsoft officials are still not talking publicly about Threshold/Windows 9. There are rumors Microsoft is planning to offer Windows XP, Windows Vista and Windows 7 users some kind of deal — possibly even a free upgrade to Windows 9 — in order to get them to move to the latest Windows version once it's out next year.