TBH, I'm not sure that Des see's Cust as anything more than solid backup material. He's had a number of chances to nail down a first grade spot over the past 3-4 years, yet still hasn't. Some of that has been injury related, but other times he's just been dropped because Des has seen someone else as a better option.
The way things actually stand, I don't think Cust has much of a solid first grade future at Manly without a lot of luck, injuries to other players or a change of coach. He's behind DCE, Foz, Walks and Froggy as a half. He's behind Froggy and Lawton as a #9 and he's behind Walks and Lawton as the bench utility (and that last is likely to become behind Froggy, Walks and Lawton when and if Fainu returns). Its unfortunate because Cade is talented, but I honestly think his talent has plateaued somewhat and I have a feeling Des thinks along similar lines.