two years at this stage in his development is about right, probably for both parties.
Its only one year less than Lee Gaskells contract, which i suspect was improved earlier than expected due to his enforced rise to prominence, caused by the Eastmond shenanigans. It would not surprise me if both are up for renewal at the same time.
By the time this contract runs out then Jamie will be 23-24 years old. We should know by then if he warrants a long term deal or if other younger players have nudged ahead of him.
Similarly for Jamie this is the perfect age to spread his wings if he so wishes. The riches of the cashed up NRL may then be beckoning.