> Would it not be better to, kind of, transition into a situation where any hardware built in the future, would be supported?

easier said then done -- the kernel's internal interfaces aren't static, they change often. The project has never committed to stabilizing it's driver api, so every driver takes non-zero work to maintain.

I would assume computers that are still running these old ISA mouses (mice?) probably are also running an older version of linux; and if they're running a new kernel then it'll be somebodys job to port the drivers forward. There's some likelihood this will end up maintained by someone out-of-tree, which is a nice way of saying "we've sent your dog to a farm upstate..."