The quota system is currently set at only three overseas (non-EU, non-Kolpak) players per club. I think Harlequins have an exemption to allow them a few more, as does Catalans, but the rest are only meant to have three?
The way clubs stretch this three is by counting some players of pacific islander heritage under Kolpak law, and by encouraging other (say Australian) players to check their eligibility for European or Kolpak nation passports. The grandparent rule is usually enough for you to claim say an Irish passport, and presto an extra Aussie can play alongside your legal three, and your other few islander players you've signed through the Kolpak exclusion.
The RFL would have to cut the existing quota down to zero or one overseas player per club for it to make a noticable difference, somthing the clubs that run superleague (and have veto power over such decisions) would not agree to. So good idea as it may be, unfortunately I can't see any progress being amde on this issue in the near future...