Microsoft has been talking about moving their web browsers to a different support model. They intend to support only the most recent version of their browser, deprecating everything beforehand. This has two benefits. First, they don't need to port security patches to nearly as many targets. Second, web developers can mostly rely upon recently added features, especially ones which do not require special hardware.
A major stage in this plan occurs on Tuesday. Microsoft will issue a patch to notify users that their old browsers will no longer receive security updates. They are ripping off the band-aid with this one, deprecating Internet Explorer 8, 9, and 10 simultaneously. Since Internet Explorer 11 is very competitive with Chrome and Firefox in terms of standards support, you will probably hear a few web developers rejoice. Internet Explorer 11 is available for Windows 7 and later.
As a side note, this also means that every supported browser on Windows from Microsoft will be compatible with WebGL. You may not be able to rely upon hardware acceleration, as blacklisted drivers will be forced into a software rendering compatibility mode, but it's good news for Web gaming.
Not by many (will be the same
Not by many (will be the same as with XP).
As a web developer I happy to
As a web developer I happy to know that