1) Make tanking easier in order to influence people to take the plunge. Obviously, this would not be a good for the game, and would be a slap in the face to existing tanks everywhere and might even have the side effect of making a noticeable percentage of current tanks ditch the role of tanking or even the entire game completely so that they can be challenged somewhere else.
2) Incorporate a need for more tanks in FATEs and RAIDs so that in order to progress more tanks are needed, thus altering the ratio mandatorily. This would be a better option, but would also skew with the numbers of FCs that are already comfortable with their numbers, as well as force players who aren't comfortable playing tanks in the first place into a role they are not fit for. So, not great for the game, either.