We are planning on using an Atem switcher to accept the SDI 30x camera feeds and do the heavy lifting, and take program out to a PC for recording and streaming via Vmix.
Is there a plugin for VMix that will offer camera control and color correction in this configuration over IP?
vMix almost meets you requirements with the proper edition in use... (Shown below are images from the 4K Edition)
The issue you will run into is going to be color correction with that switcher in-line as the same color correction profile will be applied to all inputs switched through it.
IP Control is available in vMix that allows you to take IP control of a PTZOptics camera using the cameras IP address.
You could look at bringing the feeds in via RTSP and then you could apply color correction per camera / input and add PTZ control unless you think the PC simply won't support that load.
If you have any additional questions or ideas you would like to discuss in relation to this setup or the PTZOptics cameras please don;t hesitate to return to the PTZOptics forums.