How I see Recall playing out
This post is a bit speculative, but it's informed by decades of experience.
Step 1. Get all Windows users comfortable with the idea of collecting all their data, all the time. Offer assurances that it's local-only, it's encrypted, and it's easy to opt out. Show them the benefits of Recall. (There are obviously benefits to recording everything someone does. Nobody has claimed there aren't.)
Step 2. Start pulling some data off the computer to give the user a better experience. Something like helping them plan out a vacation. Now you've got users comfortable with sending literally all data related to their computer use to an online service. Cut back to offering assurances that it's easy to opt out.
Step 3. Silently force users to opt out on every OS update. At the same time, start sending all data upstream. (It's taking up too much hard drive space, what did you expect? Of course it wasn't sustainable. And anyway, who wouldn't want a full backup of everything?)
Step 4. Remove the opt out and send all data for every user upstream, doing anything you want with it, and selling it to the highest bidder. Were there passwords, Social Security numbers, and other private information in the bundle we sold? You should know by now how things work. You only have yourself to blame.