What capabilities do you whish would be possible to do with a computer that possible with the currently available on either Amiga, x86-PC, Mac etc.. Ie not possible at all but would be really useful if was. But also within the physical possibilities.
An example is that smooth graphics was possible in the 80s but many computers tried to do in software and external logic chips what ought to be done inside a chip.
Power supplies were heavy and inefficient before switchmode ones showed up.
When processors became efficient and fast enough realtime videoencoding became possible, something impossible on personal computers previously.
etc..
