I really don't think Yamaha or Roland are going to go after the OASYS. The real money is in affortable synths ($700-$1,995). The OASYS is for Korg what Formula1 is for Honda: a way to test technology that may or may not end up in more "bread-and-butter" products. It took them over 10 years to get there.
Korg did the same thing for the Triton range (
still milking it by the way...) and they already have the new
Radias Synth using some OASYS technology.
Roland and Yamaha have diferent ways of developping affordable keyboards without having a high-price unit like the OASYS. Korg is smaller (btw, Yamaha used to own part of Korg), so every R&D dime must be accounted for. That's how I see it businesswise.
So don't wait for the other guys to "catch-up"; there's not enough in it for them.
Vermeer
"Amateur Korg Historian"