Do we really want to lock it in to a particular codec now? Newer and better audio/video codecs are released more frequently than new versions of the HTML spec.

> Will it ever be possible to do away with desktop solutions like Outlook and Thunderbird?

Why bother? I use Google's Application for your Domains for my e-mail, however, I prefer using Thunderbird with Google's Pop & SMTP interface over the web interface. I only use the web interface when I need to search through my e-mail archive.