Yes, all include/exclude functionality for HDRI and light sources are in plans. This is must have.
As for this question, I think the close enough functionality is there already:
1) You may add several Sky objects each with CentiLeo Environment tag. E.g. in objects tree there are 2 Sky objects with diffrerent HDRI (or colors).
2) In the first Sky object CentiLeo Environment tag you make Reflection Intensity = 1 and other layers Intensity = 0 (for Diffuse, SSS, transmission, Camera...). This means that while this Sky object is at the first one in the scene, it will be enabled for non zero intesity channels. While for zero intesity values the other Sky objects under it will be evaluated
3) There is other second Sky object with Env tag where all Intensity values are 1 and they will be enabled for all channels except for Reflection.

If my explanation isn't very clear, I will make a simple sample scene and upload it here. Just tell me

Kirill

Thanks Has for clarification! So, the reflections from the floor shouldn't see HDRI, but other objects should see HDRI. This is not doable at the moment, but I will work on this. Will see the practices of compositing tag. And will explore the opportunity to make HDRI per material (this can be costly) or link the material to HDRI from scene tree.