Yes, it is a "generic" film emulation Cineon to REC 709 LUT - it was not generated based on a specific monitor profile.
I think I see what you are saying. If the Cineon to REC 709 display LUT was generated based on a specific monitor profile, then you can easily remove the LUT and replace it with a Cineon to P3 LUT, which would also have to be calibrated to that specific monitor. Everything will match since the two LUTs are in accordance with one another, and with the monitor.
But if the Cineon to REC 709 LUT is just a generic one, there is no point to go the above route, things will not match anyway - one would simply convert the final REC 709 result to P3.
Of course, the first approach is the best one. However, talking about the second option... is it still acceptable to use a calibrated (not profiled - just calibrated) REC 709 monitor with a generic Cineon to REC 709 LUT? And finishing on that monitor.
I guess my question pertains to what I see around me. Many people choose the low budget approach, using generic Cineon to REC 709 on calibrated HD monitors (no probes, no profiling etc). This reduces the options, but given that any calibrated REC 709 HD monitor is a known target more or less, an the generic LUT is made for that target, wouldn't that yield good results?