HTML 5 in Windows 8 will not effect your ASP.NET development. Why?
ASP.NET == Web Server
ASP.NET is a server technology. ASP.NET gives you the broadest reach by creating HTML websites that can be viewed on any platform or device that has a web browser.
HTML 5 on Windows 8 == Client
DXperience? What's That?
DXperience is the .NET developer's secret weapon. Get full access to a complete suite of professional components that let you instantly drop in new features, designer styles and fast performance for your applications. Try a fully-functional version of DXperience for free now: http://www.devexpress.com/Downloads/NET/