I believe it can be easily controled by casinos of they set their matching systems so people from similar IPs cannot end up in the same table. It would be similar to systems which are used by cooperative games on the internet to prevent players from the same IP address from colluding against other participants.
If the people who intend to collude cannot play by the same table or are never matched together to play against others, then becomes impossible for them to do unethical practices for the sake of profit.

It would also require casinos not to allow their poker players to make use of VPNs to mask their IP address.