No it wouldn't. It wouldn't change much from what there is currently except when a review is called and the 3rd umpire consulted that the onfield umpires can make either type of call.
How would it get to the Third Umpire? As is stands, the players must make a review for it to go upstairs. In the example you gave the rugby ref makes the decision to review when he isn't certain of the call, that isn't the case in cricket, the umpire is assumed to be correct until proven otherwise.