The way I see it Inmet may HAVE to try and make a deal with PTQ to stay viable in investor's eyes as the concession-holder at CP. It doesn't matter who's running CP at some point they will have to acquire the land to build out the tailings and access to the port. That puts PTQ in the driver's seat to ask a premium from whoever the owner might be. I don't see arbitration as an option because that will take too long.
As far as someone taking out PTQ directly, that could happen, but it appears at this point FQ wants to concentrate on taking out Inmet first. Maybe they feel it would be best to get Inmet out of the way first then if they have to do something with PTQ later that won't be as big a deal.
Even if PTQ doesn't get taken out IMO they need to maximize what they get for those land rights.