And now it becomes clear!
Windows 10's summer launch date is first step in a slow roll-out | ZDNetBelfiore also confirmed that the Windows Insider program will continue after the launch event. Registered members of the Insider program who've been testing preview releases will be offered the option to switch to the Current Branch or remain in the preview program.
Those who choose to remain on what Microsoft is calling the "active branch" will continue to get new updates ahead of the public, with those updates making their way to the Current Branch when they're deemed stable enough for release.
There has long been speculation that those running Windows 10 when it becomes available will get a free copy by virtue of being an Insider. Need I say more?
If we choose to continue as an Insider, we get to keep on keeping on! I like!