No, I don't see the S12DP256 going away so easily.
I've seen that the website has a "technical glitch" (recurrent theme ??? ) and put many many parts as End Of Life.
It is indeed because the Part Number is changing to be certain we can differentiate ROHS part from those which are not. We all have to be compliant very soon !
That's where we obtained this information in the first place!
The factor in this case was apparently a serious problem at a TSMC fab. I've had an unconfirmed report that the issue has been resolved, but would appreciate some certainty in this matter.