"Intel dumped full 16 bit support from x86"
Actually AMD dropped first the Virtual86 mode in 64 bit mode because AMD doesn't know how to design an advanced chip.
It also dropped the segmentation model which will need to return if we warn really secure applications at the hardware level and not address spaces where everything is writable and executable, and just a mapping bit isolate kernel from user space.
But AMD can see only "performance, performance!" (and Intel followed, with the Spectre/Meltdown bugs) and so removes any feature to truly isolate applications and kernel.