Missing the point
I believe most of the posters here are missing the point.
This is just the final phase of Microsoft's classic "accept, extend, kill-of-non-MS-Windows-versions".
After a few fits and starts, Microsoft came out with a browser equal to Netscape Navigator. Because it was not clearly and obviously better than Navigator, they embedded it into the Windows OS so the default would be IE. Easily 90% of the Windows users switched to IE when they (or their company) upgraded to the newer versions of Windows. MS was convicted of illegally extending their monopoly in part because of this. (Their punishment? They had to promise to never do it again. Just as it was with the first "consent decree" they signed.)
The next step was to extend the capabilities of IE with MS proprietary stuff. The most recent levels of this are deep within the .Net programming that many companies are slowly moving to in their newest web enabled front ends to everything from corporate data base access to online sales. Only browsers that support the extended capabilities will be able to be used to view these sites.
Then MS kills of all non MS Windows versions of IE. There is nothing which requires MS to publish all the non-standard, MS extensions for Internet use of .Net and IE. MS does not have to publish changes to non-standard, MS specific extensions each time they put out a patch set for .Net developers or IE.
Thus all other browser developers are simply a step or two behind these MS specific extensions. The result is Apple, and others, must find out from users, "Oh, Safari does not work with this site any more. We need to find out what happened, what's changed."
Businesses are not going to go with any browser that puts them in a position to not be able to access what they need to access. A multi-day (or maybe even a multi-week) lag between MS making changes and Apple making changes to Safari to keep up will not be tolerated by most businesses.
Thus more and more users/companies will be forced to migrate to Windows. Just another example of the abuse of a monopoly position.
What will their punishment be this time? Probably no different than the last two times!