If someone is going to attack a police officer - typically someone who is physically fit, trained in how to physically subdue someone and wearing all manner of stab vests, handcuffs, pepper spray, nightstick etc, a camera isn't likely to even register to be honest. A camera is a deterrent to someone who is acting rationally - if someone is already in the process of assaulting a referee/police officer, they're past that point.
So no, I don't really believe a camera will deter anyone who wouldn't already be deterred by some combination of the kit, the cards and his teammates. All I think it will do is add a reason for someone who would otherwise be acting rationally to think they need to lay hands on the referee, to get hold of that camera and destroy the evidence of their OFFINABUS etc.
I like your optimism that the money for this will suddenly descend on us from above, but I don't really see that. Grassroots football is already in crisis - clubs are folding all over the place and the PL has yet to choose to voluntarily give it's money away to fix it. Referee retention is also plummeting - the FA have yet to try and incentivise me to keep refereeing by covering the registration fee, or subsidising my kit. In that world, I don't suddenly see £100 per referee in "bodycam grants" appearing out of nowhere.