It's not impossible at all -- Spartan is a copy of the IE engine code, repackaged as a Metro app and will be updated on an ongoing basis through the Windows App Store model. Anything that doesn't work in that space like ActiveX/COM, Browser Helper Objects, etc. are all stripped out.
IE11 will also remain in Windows 10, with good ole' MSHTML.DLL and all that other cruft that developers (and parts of Windows itself) have been taking hard dependencies on for 15+ years. It will receive security updates, performance improvements and so on, but it will not be updated at the pace of Spartan.
Maybe shipping two browsers with the OS will upset some people, but this should actually work out pretty nicely.
Intriguingly, I cannot tell whether you mean to be serious, funny, or sarcastic. I simply don't know enough about windows to tell...
Why won't sharks eat lawyers? Professional courtesy.