Things I need before I'm going to pretend IE isn't a steaming pile of shit, hell I'd settle for just 1-2:
* Evergreen browser (I'm sick of dealing with 7/8/9, I don't look forward to playing the same song and dance with 10/11/12/etc)
* Cross-platform (Testing on Linux or a Mac is painful)
* Open source (IE is the ONLY major browser that is not OS, and yes I know Chromium != Chrome but I'd be fine with IE doing the same sort of thing)
Still a bit worse than the others, but Safari has also lagged lately (and Safari also isn't evergreen).
(I agree with all of the above for the older IE < 10)
Interesting, as their partner for Modern.IE, BrowserStack, uses a Javascript based remote desktop. (It may also support Flash on certain browsers, but I'm not sure about that part.)
Maybe.
> This new rendering engine was designed with Project Spartan in mind, but will also be available in Internet Explorer on Windows 10 for enterprises and other customers who require legacy extensibility support.
— from http://en.wikipedia.org/wiki/United_States_v._Microsoft_Corp.
It is always write once, debug everywhere and always will be.