Do you think Apple should create a proper successor to the Fusion Drive?
Ok, just some notes regarding the Apple Fusion Drive.
A Fusion Drive is a software-managed hybrid drive of a fast drive and a slow one, using Apple Driver software.
It is made up of two separate drives, typically a SSD and a HDD.
It is a competitor to hybrid drives which combine a fixed SSD of 8 ~ 16 GBytes and a HDD in a single unit, and is managed by drive's firmware.
My iMac has an internal Fusion Drive, with the SSD component being 128 Gbyte (much bigger than a hybrid drive) and a 1 TByte HDD.
I have also created an external Fusion Drive from a USB 3 Flash Drive and a USB 3 HDD.
A Fusion Drive only works under macOS. Consequently, when Bootcamp partitions a Fusion Drive to put Windows on it, it doesn't touch the SSD component, it only reduces the macOS partition of the HDD so that a Windows partition can be created. This means that when you install Windows under Bootcamp on a Fusion Drive, the Windows partition is HDD only.
Under previous versions of Windows (up to about Win 10 2004) it ran very slowly under Bootcamp, to the point it was nearly useless. Starting with, I think, 20H1, Microsoft improved the responsiveness of Windows on HDDs, so that it was at least bearable. Under Win 11, responsiveness has improved to the point that it is practical.
I think that Fusion Drives and Hybrid Drives are an interim measure until SSD prices drop some more.
A HDD is a complex mechanism, that must be costly to manufacture, even if the components are cheap.
A SSD is a simple mechanism, that must be inexpensive to manufacture. We just need for the price of the components to drop some more.