Not to knock a good conspiracy theory, but there are a couple of holes here.
1. You assume that all cars will have dash cameras. And that they will work all the time. This is just not the case. They're expensive, electronic, and they spend their lives in a harsh environment where they're barely taken care of.
2. You assume that the "central" database in question will always be available for querying. I don't know the exact uptime stats for the NCIC database, but I'd guess its around 70%
3. You assume that there is a way for a camera system to have a continuous data link with the "central" database. I don't know if you spend much time outside of town, but that's just not the case either. I know of 50-odd places in just my county where I can't make a phone call or get out on my radio, let alone get on the internet.
4. You assume that there is a way to link together 4 different databases in a way that is robust, reliable, and actually works. Right now, for me to get a CHL status from a license plate takes 4 or 5 minutes if dispatch isn't busy. Even eliminating the human element, it won't be fast.
5. Assuming that you have a bad apple who is going to pull you over based on a hit from a camera system, that means the camera system is operational, and that he will have to come up with some actual probable cause to pull you over. And PC isn't an excuse. It is defined in statute and case law.