For Piano Players
If Piano-System was only bad, it wouldn't have survived for such a long time:

To show one clear major and minor scale on the white keys is very helpful, especially for beginners.

Such a "beginners-system" could also leave away the black keys and show the white ones in such way to prepare for the new layout:

As soon as key-changes of music is practiced, the piano system might be replaced by 6+6-System to practice a more common way for all scales. If not for the Piano itself, it is highly recommended for the Accordion, where the left hand already plays all scales in the same way.
Here you can compare both systems by yourself: Old - New

Good piano players deserve respect for their achievement.
They practiced for a long time and don't have to start again with the new system. They only shouldn't repeat the fault of their teachers: They should not prevent new generations from playing the new system!

Piano players are often those musicians with the deepest understanding of the harmonics in complex pieces of music.

All this knowledge stays valid with the new key layout.
So teaching of music won't change very much by the new 6+6-layout.