I'd say either the Freedom, or the Hyaku-Shiki are next in line.
I doubt that.
Given the history of PG kits, I would say that neither of those suits are really plausible at this point.
HERE are all of the PG releases to date....
The only series that has given us multiple Gundams was Z / ZZ with the MKII's and the Zeta.
The HY2M line looked like it was picking up where the PG's left off with the Zeke suits, when they gave us the Rick Dom, and the Gouf in pretty short order. However, that line looks like it's DOA now.
Given Bandai's history of releases, I would not be surprised to see a Strike Rouge, since they can do it on the cheap like they did with the Titans MKII. But, I don't think we will see the Freedom (at least I hope not). The only really cool SEED suit was the Strike Gundam. The rest of them were really too Wing-ish for me.
I really doubt they are going to shove more Z or ZZ down our throats by doing the Hyaku Shiki either. Also, with all the gold on that thing, it would be an Elvis esque monstrosity, a pimpin Gundam paradise.
I just hope that they head back into the UC, and give us a freaking Alex, EZ8, or RX-79G. I would love to see more Zeon suits, but let's stay out of the OYW era, and get some new stuff going, Kampfer, Jagd Doga, Geara Doga, Sazabi
Or, if they decide to stay in AU, at least give me a Heavyarms, which was the least gay suit out of wing.
And if they start making G Gundam suits in PG, I will have to burn down the Bandai factory.