Technically it will work but may not be optimal. You'd need to determine the difference in output between the MVS and CPS2 and compensate accordingly by adjusting the values of R1 through to R8, which act as a voltage divider upon input to the THS7374.
That circuit seems to indicate that MVS has an output of 4.1V. I do believe CPS2 runs a little higher than that, so stronger attenuation will be required (refer to voltage divider resistors mentioned above).
I'm not 100% certain however I feel that circuit is flawed. It high pass filters the video signal and due to the high value of resistors used, it will disable the clamp function of the THS7374. Ultimately this may not be a problem but it's not the optimal way of doing things and may result in distortion.
There's a better version of that design that has been used by a few people now (I have 3 built on my bench)
I had similar thoughts on how easy it might be to adapt to other systems, as Frank_fjs said the resistor values will need to be modified.
A couple of people in this thread did exactly that because they weren't happy with the brightness of the output.
Anyone using a CMVS-RGB pcb for MVS SCART/RGB?