There should be one, but it can be improved a lot. Considering that countries name a roster of 24 players, each one should have to name a minimum of 7 domestically-produced players on their tournament roster, players who played their first senior (i.e. open age) RL in that country. They could be players still playing in the domestic league or they could now be playing pro RL somewhere else, but they would have to have started playing senior RL there. That would leave a maximum of 17 roster spots for players who qualify purely due to heritage or residence. Once the roster is named, no additions or replacements should be allowed for any reason (including injury) unless they maintain or increase the team's domestic player content. In short, 7 or more domestically-produced players on every team's roster at all times, no exceptions.
The only way of improving the domestic rule, is to improve the standard of the domestic competition. How an individual nation does this is up to the individual nation because each nation is different.
A lot of people seem to forget that the World Cup does have a domestic rule still. The rule is that to play in the world cup you need to have a domestic competition. The last World cup saw this rule bent for a couple of clubs. This time that will not happen and will not need to happen, because the clubs that it was bent for have all (except for one that no longer plays) improved to the stage where they have their own domestic comp. This means the next World cup will only only feature bona fide nations. That is a step forward.
IN fact, some bonafide nations will actually miss out and not qualify. That is a step forward also. South Africa, Jamaica, Serbia and possibly even Russia are sides who 20 years ago would have been the 6th best nations in the world (maybe even better) but who today will be doing well to make the top 14 under any rules. That is progress, and that means that regardless of who is selected, this world cup is a serious event in anyone s book. There is no longer any need to worry about artificially creating the image that the game is played domestically in certain countries, because if they are in the world cup, it is.
The next advance should be not an artificial distinction, but simply a return (and it is a return because it always has previously been the rule) to one nation for life. In fact, if the RLIF is hellbent on it, I would even consider allowing one (and one only) compassionate change of nation for a player, provided that this player is moving from one of the big 3 to a smaller nation. That is a far bigger problem than forcing domestic players to play.