I see MS making money the way software companies make money, not the way search companies do
I expect that MS will shift to making money the way money is made off of Linux.
An increasing portion of the revenue will business clients paying for training, support and additions to the operating system.
It will also make an increasing portion of its revenue from cloud services.
Apple, Adobe, Sun (and Java), Mozilla, they all make money advertising other people's products, and MS does too.
But I don't see MS going down the path that Google did and becoming primarily an advertising company.
For one thing, MS is widely used in governments, businesses, classrooms and they'd loose that business if they tried pushing ads in the volume Google does.