There have been a few projects which tried to add support for a new model format but none were finished.
In any case, .blend is not a good final format for FSO since it is not designed for that use case since it is more of a model exchange format. .dae has been discussed many times (and PCS2 has support for that) but even that format is not ideal for FSO. I looked at glTF 2.0 and that looks pretty promising but the biggest problem here is that the collision information required by FSO would first need to be computed which would increase load times significantly.
However, you can use Blender to export a DAE file and then use PCS2 to convert it to POF.