From my research, an org can have a mixed user policy; meaning that a subset of users can be on a full Salesforce license and a Force.com app license (or any other combo, I believe).
One of the limitations of the Force.com app license is the number of custom objects that assigned users have access to. I'm not sure what this means for a mixed user policy implementation.
For example, if an org has 250 custom objects, and the Force.com app license negotiated has access to only 200 custom objects, then does it mean that a mixed user policy implementation is NOT possible until the count of custom objects in the org fall below 201? Or, is it possible but a pre-requisite is that the object access on the Force.com app license has to have read/write access to a max of 200 custom objects?