I wouldn't be surprised if you found yourself facing a united (allied) front consisting of AS, Ptol, and Pontos at some point. Plus, you'll most likely be at war with KH, Maks and Getai if you're planning on expanding into Thrace.
Some of those Thracian elites will certainly come in handy dealing with all the Galatian heavies Ptolemy will throw at you. Sounds like fun. Good luck.