It will be interesting to see what happens the next time Apple needs to drastically overhaul their language and how gracefully it gets handled. I think they did a decent job in handling "classic" applications.
Why can't Microsoft do the same thing? Abstract out support for old versions and build something concrete that can be expanded. OSX has been around since 2001 with steady improvements with each upgraded version. A lot has changed on the outside as well as under the hood but the same core architecture is still in place. Why? Because it works very well, is modular, and can be improved without a massive overhaul.
Windows 7 is rumored to be going on this path (emulation of old windows, modular, ...)
but honestly I wonder how many of these new promises will come about. I still remember the old promises about Longhorn aka Vista. Their new filesys (i think winfs) is no where to be found, and their cool looking command line is just starting to show up on server 2008... M$ has a bad history with promises and reality
Why can't Microsoft do the same thing? Abstract out support for old versions and build something concrete that can be expanded. OSX has been around since 2001 with steady improvements with each upgraded version. A lot has changed on the outside as well as under the hood but the same core architecture is still in place. Why? Because it works very well, is modular, and can be improved without a massive overhaul.