T3 PA is probably right around the corner and you just know that there are people out there with enough points bank that the will probably be able to get most of the god stuff the instant they go live. But what next? Are we going to continue going through the same things over and over again with just minor tweaks? Hopefully not. That is why I am sudjesting that the next tier of advancement after T3 should be soul advancement.
The concept is simple each soul would get a tree much like the current PA trees but it would enhance things already in the soul tree or that would make sense to go with that tree. They could even add new abilities this way. This would allow players to customize their character even further in a way that the raw stat increases in the current PA trees do not. Some of the abilities and effects would be universal and some would only apply when the associated soul was active. And by the time they get around to this there will be 9 souls per class so that would be 9 more grids worth of PA to fill in. At the very least it would be a more exciting system then is currently in place.