Doubt it. Metro IE doesn't support any plugins, no Flash, Silverlight, Adobe Reader for you. Compatability with IE6 is also pretty nil.
I don't think you'll win many corporate users just with a barebones HTML 5 browser. It's obvious to me that MS knows and it too and that's why they want push Metro.
Outlook - what about Powerpoint, Word and Excel? Word is the bread and butter program in lots of cases. Attorneys can literally close shop without it.