Certainly in applications I believe there will be a greater takeup of Open Source software. I do not see Linux becoming mainstream in the foreseeable future.
As a NON technical professional person with a strong IT interest, I have been running Ubuntu 9.1 as well as Mint in Virtual Box as well as on separate drives to see for myself. My kit is pretty up to date. IMHO is that until some hardware compatability issues are resolved and application installations are as simple as Windows, Linux will continue to play second fiddle.
BTW, I think Linux Mint8 is a lot easier to use than straight Ubunt 9.1.