Further to foggy's question above, I looked up the latest version of the membership rewards terms and conditions I can find for the DJ Amex:
https://www.americanexpress.com/en-au/rewards/membership-rewards/getWebImage.mtw?webImageName=new-david-jones-mr-tncs_2019.pdf
Hilton Honors is still listed under 11.4.
15.2 We may vary the number of Membership Rewards points required to purchase a specific reward at any time without giving you prior notice. However, we will give you at least 60 days notice if we choose to significantly increase the number of Membership Rewards points required to redeem rewards as a whole unless this increase is as a result of an increase in the cost to us in providing such rewards.
15.3 We may remove rewards which we believe are not material to the Membership Rewards program without prior notice. This may include the removal of certain rewards partners and/or the removal of certain reward products supplied by those partners. For rewards and reward partners which we do consider material to the Membership Rewards program we may remove such rewards on giving you no less 90 days prior notice provided that we shall not be obliged to give you notice if the removal was required by law.
As far as I'm concerned, I still have not been notified of the increase in points for transfers to HH (60 days noticed required, and I would consider doubling the points required as significant) nor have I received any notification of the removal of HH (which I consider material).