html5 impact and questions

Question

I keep hearing about html5 and seen on other questions/answers on this site that the current browsers do not yet support it...what I know:

• it has potential to replace flash and silverlight
• Google seems to be building new systems to take advantage of it (is that correct?)

What I don't know (which is a lot, but will limit it to some points of interest):

• how will existing sites work within a html5 browser (backward compatible?)
• is Flash/Silerlight really gone? will they be supported? (I'm sure adobe will not be happy)
• is javascript impacted? improved? will jquery still work?
• is there a good site listing (high level down) what the html code impacts are?

Answer 1

W3C has a working draft of the differences between HTML 4 and 5.

Answer 2

Google seems to be building new systems to take advantage of it (is that correct?)

Correct

Google Bets Big on HTML 5: News from Google I/O

HTML5 and The Future of the Web

HTML 5 is a mess. Now what?