I predict that Microsoft will give away or charge under $100 to corporate users of their Office application by YE 2009. Perhaps it will be a downgraded version. Maybe they'll release the full-blown one. I don't know.
As Mac/OS X and Linux increase their market share (inevitable looking at worldwide numbers), Microsoft will be compelled to use their office application to tie users to their ecosystem.
Don't forget they have their success riding on users sticking with Windows. Why? Think of their development platform, .Net, which only runs on Windows. What about SQL Server, Windows Server, Dynamics, Silverlight, Sharepoint, Exchange etc. The reason these are more compelling than competitor products in that they are tightly tied to one another. Office and XP/Vista are the glue. It won't work on anything else. So as other operating systems become more compelling, free/open like Linux or just plain better like OS X and OpenOffice is free and collaboration is getting better and better (and free) on the Internet - who would pay $488 CAN for an office license?