I am in much the same position. I have about 180K in Amex and another 80K in Diners Club cards. These are in addition to alomost 400K in QF. I am still expecting to eventually transfer all the Amex and DC points into QF. But they will remain in CC accounts until I need them or close out the CC account.

You don't mention your reasons for closing your Amex card. Assuming this is due to your mentioned retirement (and it was a company/business card), you could continue to hold and use an Amex card such as the Rewards Maximiser card (which is what I now have) and earn more points at 1.5 per dollar, which is a better earning rate than most.

But if the Amex closure is non-negotiable, then if it was me I would be sticking with sending the points to QF. Mainly since you have top tier status with Qantas and will have no status with any other program you send to. My feeling is better to pool the points into one program where you hold status rather than spread them to other programs.

But I do not always think like other people, and others may have different advice or may do different things in your situation.