[O____________O]

Is there some proof of this outside of this USA Today article?

I came here with the exact same concern as the GP comment.

“We’ll continue to have Internet Explorer, but we’ll also have a new browser called Project Spartan..."

It just reeks of marketing double-speak that gets engineers excited, only to find out that they're stuck maintaining code for N + 1 browsers now.

Incidentally, Microsoft rebranding exercises infuriate me. Arguably, Spartan is a "new" product, but by that measure any product rewrite should get a completely new, unrelated name rather than a version number. I remember COM + DispInterfaces ==> ActiveX, Outlook Express ==> MSN Messenger, MSN ==> Bing. It's just irritating and confusing to both developers and consumers.

[gsnedders]

AIUI, the version of Trident (i.e., mshtml.dll) shipping in Win10 is that of IE11. There shouldn't be any behavioural changes, and Trident should only be used in IE12 for intranet websites by default.