How long until the average halfback is 6 ft

Just thinking rugby players generally seem to be getting bigger and bigger in their positions. In a contact sport where power and speed are ideal, it seems almost out of place for a small, light player to be out there. Wondering when coaches will select bigger, taller half backs that are just as capable as their smaller counterparts. Also makes me wonder what it means for the future of the game and how accessible it will be for non-freakish sized athletes