Many overseas airlines already have commuting 'guidelines' in place based on travel time to commence a duty, whether that travel is in your car, in a middle economy seat in the back row, or 1A. In most cases these guidelines are non-specific in terms of proposed duties and include minimum pre-duty rest periods (a lot less than 24 hours) in suitable accommodation - that is, not a crew room couch or a terminal seat.
As is currently the case, any decision on a person's individual fatigue can only be made by that person. This will not change even if guidelines, rules or CAO's do stipulate requirements. The only difference will be that a person - pilot in this case - will have to justify a breach of the guidelines/rules/CAO's in the event of an incident or any event which impacts on the regulatory or commercial viability of the operation.