Well, the biggest retailrer, Wallmart, is already doing it and selling them for $200. This will spread eventually to others and will show that Linux is viable and create more demand. With more demand will come the solution to some problems such as hardware vendors not writing drivers for Linux.
Also the adoption of Linux on servers will put pressure to put entire businesses on it. No reason to have two sets of technicians, the problems of mixed systems when most employees do not use even 10% of the capabilities of their systems. Plus if all are on the same system there is no problem of file sharing.
And let's not even talk about security...