I personally seriously doubt that DCX will do anything beyond stage 2 for the PT. The new redesign v6 cruisers are comming around the corner. I'm pretty sure those things will not be as quick as the PT GT's currently available, but would produce more than enough power for a daily driver.
A few other factors will stop the PT GT from becoming an SRT-4 Wagon (or any additional ponies comming):
1. Price for a GT $22,500 w/ rebates and incentives aren't bad (but w/o rebates it goes up to 25k easy). DCX would have to figure out how to bring a cruiser's price down to the younger crowd. Maybe a strip down verson of a PT GT with alot of amentities missing and more sports tunning. The target price should be close to the Dodge SRT-4 (a little higher since its a wagon/truck/<insert your class here>
2. The image of a cruiser is a hard sell to the young crowd. Alot of people believe the cruiser is for older folks and moves like a turtle. Personally, I'm against street racing, but to improve the image of the cruiser, it has to demonstrate its perception that its an affordable pocket rocket.
To sum up my point, you need the younger generation to justify more ponies to a car.
My solution:
1. Create a 2005 PT (Chrysler SRT-4): Same Amentites as a Base Cruiser, except you get a LSD, better motor mounts, 2.4L Turbo Engine, and 5 Speed Manual Standard (debatable to have an auto option, but the v6 cruisers are comming

)
2. Need people take this car to tracks, events, any where you can show that the cruiser is a fast car. I'm against street racing, but its probably one of the things that hit home on sports compact cars in justifying an existence of a fast car and the justification of more power neeeded.
3. Give Car & Driver, Motor Trend, Automobile Magazine, or whatever magazine a MANUAL PT cruiser to test. As of today, I still do not see in magazines or websites offering the times of a stock manual PT GT. Key point here is perception ----> FAST ----> Justify a car to have more ponies.
What really will happen:
THe v6 version cruiser will come out, it's doubtful it'll be turbo charged. I sincerly hope that a turbo charged v6 cruiser comes out, but reality there is no justification to make a Chrystler SRT-6 Cruiser. Our PT GT's will go down in history as the fastest production PT models produce, so keep it in the garage

.
Yes, I'm a little of a doomsayer of the future of the PT GT models. Sincerely, I want the GT's to get the status of SRT status and more ponies, but with no "fast and furious" kids and die hard speed demons, the cruiser will just be a cruiser to everyone around me.
Yes, the PT GT is the fastest car evar. Drive On. [8)]