Does this mean we could have a new ROM chip fror classics, with new stuff built in?
That remains to be seen. There needs to be some serious optimization or other trickery applied to make it possible, as currently the image is way larger than 512KB.
One possibility could perhaps be to use LZMA compression for the image, but this would mean losing quite some RAM for the decompressed KS ROM.
Since UAE has no such size limitations (or the limitations can easily be worked around by locating part of the KS ROM elsewhere in memory) it will easily benefit from the new AROS KS ROM. Classic KS ROM replacement will take some more effort.