Oh it would be a huge step up in quality in the cameras.
Forget about the nice static image it probably produces, once you dial in the shutter/exposure speed (min 1/60s shutter to minimize blur) you will see the limitations.
They sold you cheap consumer grade 8MP cameras on the same sensor as a good 2MP. The 2MP will kick its butt all night long.
Any 4K camera on smaller than a 1/1.2" sensor will be horrible for night vision.
Almost any camera can do well in the daytime with enough light, even cameras that are 8MP put on a sensor designed for 2MP. But keep in mind that usually the processor and other stuff are still designed around 2MP, so the camera struggles trying to keep up with 8MP worth of data.
So buying an 8MP camera on the same sensor as the 2MP processor means that the processor is potentially working 4 times as hard for the 8MP camera. The camera you have was designed for 2MP, so when they pop an 8MP lens on it, the processor is still the same and has to work harder. In some situations that is problematic. Thus one of the reasons why it didn't have AI in it.
Here is a real world example with a deer. Even with a floodlight, there simply wasn't enough light to make the 4MP on the sensor designed for 2MP to go into color. Imagine how much darker trying to squeeze 8MP on it will be and without a floodlight, forget about it.
And a 4MP on the proper 1/1.8" sensor camera (different deer LOL but same field of view when the camera was replaced to a better camera) that the camera was able to go to color based on the larger sensor:
Which do you think is the better image? The same thing applies whether it is a 4MP versus 8MP on the sensor sized for 2MP.
But an 8MP will be even worse because it will need even more light than the 4MP on the same size sensor.
Then you have to take into account how far you want to IDENTIFY people - the cams you have will be limited to about 10-15 feet at night.
