Although they very well could do something like this, I wonder about the efficacy of it. First, this would only apply to guests with MagicBands (resort guests and AP holders who didn't opt out, other guests who opt-in with the charge) with a functioning transmitter, and a smartphone with the app loaded and notifications enabled.
Then they have to have noticed they got the notification, and then be willing to be diverted. I doubt you'd get my family to cross the entire park for one ice cream when we've got our plan.
Range could limit it as well, if the reported 15 ft range is true. Depending on where the receiver is, by the time the system could react, and then the guest reacts, etc. the guest could already be in line.
And how much impact will it really have? I think they'd really need to look at the larger scale vs. individual guests (i.e. the "mob level"), and location info is less relevant then.
I could see a little more of them knowing where you were at least recently (say, at Space Mountain), and sending hints or "Surprise FP+" to underutilized people-eaters (like Carousel of Progress) similar to what they do with the Surprise Fastpasses now, but better targeted.
Lots of questions remain to be answered.