Sorry to be a downer but it will happen if it hasn't already, and the biggest reason is cost savings which is pretty hard to argue against when the budget is up for discussion at the local gov.

Having drones patrol large areas, running plates and face-matching against a warrant database is much quicker and cheaper than having people doing it. They're also cheaper than helicopters to follow fleeing suspects, and a bit harder to detect.

I agree though it's a huge privacy issue here, but when it comes down to money it'll be a tough fight.