That would be a decision for the hardware manufacturers to build support for USB keyboards into their computers and for the customers to buy them (and they did, but it took a long time for PCs to drop the AT connector and you can still buy AT-USB adaptors). This is more like an OS upgrade for existing computers dropping support for the numberpad for no particular reason. It won't affect many people but it will affect others.
I really see no reason to drop support for 32-bit Intel software if the OS is properly architectured and ARM support is around the corner anyway. The ARM version of the kernel would be a different OS build anyway with its own set of bugs.