With Windows 10 due out in just over a month, Microsoft is keen to make sure there are lots of apps available. So it's not surprising that preview releases for Visual Studio 2015 will now be aligned with the preview updates being sent out via Windows Insider.
Microsoft outlined the sped-up release cadence in a blog post this morning:
Starting this month, we will release previews of the Windows 10 SDK more often to our Windows Insiders. Our goal is to release a Windows 10 SDK preview that corresponds to OS flights delivered through the Windows 10 Insider Preview Fast Ring. As part of these preview releases, we will also release a matching version of the Windows 10 Mobile emulator. While we’ll do our best to align with the OS release schedule, it is possible that not every OS release will bring an updated SDK.
I'm not sure how many new releases the Visual Studio team will manage between now and July 29, but it will be interesting to see.
Getting ready for Windows 10 — SDKs, compatibility, bridges [Building Apps For Windows]