If a device is still on the webpage then it is not fully discontinued, but doesn't necessarily mean that it is currently being built. Due to chip crisis I assume that only the newer designs are being manufactured where the higher demand is ...
The ADI-8 QS is a pure MADI device, designed 2007, M-32 and M-16 converters are from around 2009.
You should compare the technical specs and features and then come to the conclusion whether you want to have older MADI-only devices (maybe from the used market) or devices which are more modern with most likely better specs and more options.
The newer devices all support - besides MADI - also AVB and some also Dante (the models with -D in the device name).
The newer devices are:
M-32 AD Pro, M-32 DA Pro (MADI, AVB) from around 2019 (newer models since 2023: M-32 Pro II series)
M-1610 Pro (MADI, AVB) from around 2021
M-32 Pro AD II, M-32 Pro DA II (MADI, AVB), from 2023
M-32 Pro AD II-D, M-32 Pro DA II-D (MADI, AVB, DANTE), from around 2023
The best choice for you most likely the M-1610 Pro, offering 16 ch AD and 8 ch DA, then you need to buy only one device.
With the M-32 series, you need two devices, one for 32ch AD and one for 32 ch DA.
BR Ramses - UFX III, 12Mic, XTC, ADI-2 Pro FS R BE, RayDAT, X10SRi-F, E5-1680v4, Win10Pro22H2, Cub14