The impression I get from this site and similar blog posts:
IE 11 ends with Windows 10. Edge the Browser isn't classified as a Windows component, to my knowledge, and so also shouldn't classify for "extended support" like IE has in the past. It certainly sounds like the intention is to drop IE entirely once Edge has feature parity and user adoption on its side.
(Things are a bit trickier when talking about EdgeHTML the Renderer which I would think is a Windows component still, given that it runs some of the Windows Universal Platform, but here also the benefit of forking it from IE is that they can keep the support policies clear from day one as opposed to having to fix up things after the fact like they did here.)
Edge cannot have feature parity. For example, it will not support plugins. I don't think they can drop IE from Windows due to enterprise use and LOB applications.
By parity here I do not meant "exact same feature set" or even really "equivalent feature set", but "enough features to get the job done and feel like a real browser". For instance, Chrome-style JS extensions (~plugins) are coming soon enough.
Beyond that, if an enterprise has not gotten the message not to build LOB applications as browser plugins and not to build for one and only one browser model any time since IE6 has been deprecated, then IMNSHO they deserve what they get when IE11 dies as the last "IE". Given the support timeline expected for Windows 10, enterprises have presumably roughly a decade of extended support to adapt before IE dies. Really hope enterprises are paying attention to that (but of course we know a bunch will not and will complain in ten years about lack of support and those of us that got the memo today can proudly mock them then).
