Hang on.

Poser has the Add-Ons system which already allows for third-party plug-ins - for example, look at the Reality bridge to Luxrender, and the Octane plug-in to Octane Render. (BTW, Octane has support for Instancing so if you're using the plug-in you can do Instancing from Poser ...) Therefore someone could make a bridge to Iray (though I personally wouldn't see much point, but hey).

If you want cross-app compatibility with materials look at PBR Metal/Rough or PBR Spec/Gloss workflows, which Poser supports via Cycles, does a sort-of reasonable approximation via Firefly, and are also IIRC supported by Octane and Iray - along with many other apps these days.

Poser also supports FBX - while I haven't used it much, it does provide the possibility to transfer simple rigs between different apps and is used for games. Not sure when that was last updated though as FBX is proprietary and there are several different versions.

Point being, while there is plenty of stuff that could be changed/added (and that will never change no matter what happens), there are already things in Poser that seem to me to be under-used, or even ignored ...

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