I wouldn't count on any other browser to be anywhere onboard with that. Chrome is known for implementing things in a quick and dirty way with complete disregard for input.
Also, Fugu will definitely no bring a signinficant amount of native APIs to the web. Here's the full list [1]
For example, the post I'm replying to mentioned Ableton. Well "I don’t know who the Web Audio API is designed for" [2] Oh, and then there's no guarantee Chrome will not break it the way it broke automatic audio previously [3]
The web is not the long-term future for any foreseeable future