There was a very similar thread from way back in November in the Tanking Roles forums. Folks might find lots in there worthwhile.
http://forum.square-enix.com/ffxiv/t...ming-new-tanks
Informed by that thread and by my own views, I suggest the following:
1. The main reason for a tank shortage in this game (and indeed all mmos) is not that there is a shortage of tanking classes but that not all players enjoy tanking. Yes, the imbalance might be lessened by group sizes of 5/10 rather than 4/8, and maybe more interesting tank types and a less toxic community would make a difference too, but only around the edges. There's a certain visceral joy in the killing stuff role, plus one is less exposed to group angst.
2. That said, the imbalance is likely to be made worse if new dps classes come out without bringing out a new tanking class as well. Without a new tanking class we would see lots of players playing up new dps and no tanks being played up at the same time. Now, granted (see #1), those playing up the tanks are more likely than not players who already play tanks, but still...
3. In the end, only mitigation tanks work. Pure evasion tanks are either ghods if they can evade everything or they are broken if they
almost evade everything. That is, they are ghod-like until the RNG wins, and then they are just dead. In the same way, a pure self-healing tank doesn't work. If a tank can't take the big hit it doesn't matter how fast it can heal itself up afterwards if it's already dead.
4. Nevertheless, there are tons of different class mechanics that can be used to mitigate. There is plenty of room for SE to bring out a new tank that does the same job (holds aggro and takes a beating but keeps on ticking) but in different ways.
And frankly, that's all I remember as bottom line conclusions (at least my take-away conclusions) from that long-ago thread.