Could it be possible to sell ownership of a pool?  Of course, your still end up potential for individuals to take over ownership and change fee structure of pool, which woul still be unfair to miners...of course, current owners could also do this.

Is there anything to stop pool owners from charging an entry fee and then a week later changing the fee structure to a very high fee, thus making the entry fee unfair or do owners choose between an entry fee or a fixed block fee.