One thing to consider is that right now a large percentage of active players have leveled every available class to 50 and are geared to at the least i100 on all combat classes. Even those they don't use often. This means that players who play tanks primarily, secondarily and even tertiarily are available to tank content. This gives us an apparent surplus of tanks.

Once Heavensward hits on Friday morning we should start seeing the primary tank population separate itself from the secondary and tertiary tank population for a few months.