Sadly, that's not realistic. You can get a subset of users to pay, but it's vanishingly small compared to everyone who thinks they are perfectly happy with the "free" status quo. Even a dollar a month, it is infinitely more than zero. I just had this conversation with members of my extended family and almost all of them were of the "I don't care if I'm tracked, I've got nothing interesting to hide" mindset, along with "not a chance in hell I'm going to pay for this, or email, when I get them from Google for free."