I suspect the appeal of an ad model is that it's perpetual recurring revenue. It's the same direction they go when they desperately push subscription licenses

I suspect the appeal of an ad model is that it's perpetual recurring revenue. It's the same direction they go when they desperately push subscription licenses (see: Office 365) They want a business model less dependent on people replacing their PCs every three years. I don't doubt they see a rapidly approaching future of management saying "these computers are more than adequate for office work and web browsing, so we won't replace them until they physically fail in 5+ years." It's an easier and easier argument to make, especially when we're running out of easy, cheap across-the-board performance boosts. (Office and Chrome don't run that much better on a new 32-core Threadripper than on a second-generation i5)