i think that once html5 becomes part of the standards it will work with all browsers 
it is part of the standards. Otherwise, FF probably wouldn't already have support for most of it's features.
it's a matter of the browsers playing catch-up. It's better this way. Before browsers were adding features that weren't in teh standard, like OBJECT tags and APPLET and BLINK and other cruft, and then they would have to decide at some point which of these stupid retarded and often OS-specific features would make the cut as a standard. This often took years. Heck, Tables were a de facto standard that didn't even officially exist as part of HTML for years and yet were implemented by nearly all browsers at the time, and only later actually added as a de juere standard with well defined rules. Before that they just sort of made it up as they went along.
Remember the absolute MESS that was working in web design in the days of IE4/NS... and... whatever other browsers there were back then? even between those two browsers it was like trying to capture a shaved greased up gorilla to get a page working right. They both essentially had their own set of standards (being that most of the "standards" were de facto). the browser compatibility nowadays between the major players- IE, FF, Chrome, Opera, and others, is a mere sliver compared to the absolute hellish experience it was trying to get a page working in all browsers when there essentially <was> no standard* by which you could follow.
Nowadays, thankfully, the standards are created <before> they are implemented, so we actually end up with stuff that is in general well thought out, not garbage spur of the moment "hey wouldn't it be cool if there was a tag/attribute for" crap made by one of the developers of a browser on a random whim (I'm looking at you blink,marquee,animate,audioscope,bgsound,blackface,bq, etc.)
*OK,so there <WAS> a standard, but if you followed the standard all you'd have is a drab boring page, with no javascript, CSS, and using only very basic tags and attributes. Trying to create a page that looks good using them is like trying to sculpt Michelangelo's Davis using Oven Mitts stuck on the end of barbecue tongs, or trying to grow watermelons in easter grass- the best you can hope for is a huge mess.
