Rob BowmanAm I wrong, or does Conditional access not already work with O365 apps, which include OneNote?
As for the announcement, OneNote for W10 now has numerous features that the W32 does not have. Maybe MS thought it was a good time to reiterate, yes reiterate, that no more development of W32 OneNote would be happening. This actually isn't the first announcement, but perhaps with recent development of the app it is a well timed reminder. This is in keeping with MS strategy of outlining road maps. There is nothing wrong with announcing a change that will happen in 1, 2 or 7 years down the road, especially when I am certain they have millions of users who will never touch the w32 version of OneNote.
Regarding search, or any other feature: Always remember to try the keyboard shortcuts. Like with the Equation editor. Many more things have been ported than the UI shows. Sometimes the keyboard activates them.