I agree with that, but the same could be said of any player. Your best players aka Hamer and Seriki are naturally going to want improved terms when they know that they're the best players, but within reason. They're unlikely to get ousted by a homegrown player.
Starting negotiations in their final year is naive as you have until January 1st to get them to sign or they can sign a pre-contract agreement with other clubs, or you accept that they're not going to sign and keep them until the end of the season in the desperate hope that you'll get promoted and they'll sign a new deal in the summer, or you sell them for a crap amount in January as clubs will take advantage of the contract situation.
I don't have much faith with our club as we seem to always end up worse off with sales, contracts expiring etc....