I guess there are a heap of possible variations that could be used to modifying the inter-change.
Another bonus in reducing it is that many current players at the top clubs who are regularly on the inter-change bench may want to move to another club to get more game time. Might help spread the talent a bit further.
Perhaps the inter-change could be limited to using only two players in the first half, and then increasing it to four in the second (and possibly requiring the 3rd and 4th interchange player to have played in the Under 20s game).
As an example of the difference a reduced interchange could benefit the game, have a look at the Qldrs in Origin 3 (put aside the Johnston concussion issue) - dug deep, and everyone applauded their gutsy effort. I'd like to see more of it.