The impression from inside the cellular structure of Radio 3, where no one knows anything about anything that doesn't concern them directly, is that, yes, Discovering Music is to be axed. Those 90 minutes, plus another 30 gained by chipping about with jazz programming, will provide the time for the new guest-presented Saturday Classics, 3pm-5pm. No response to my query on the New Season blog almost a fortnight ago, and no reply to my email direct to the programme. The BBC information line has no knowledge beyond the Liszt programme on the 14th.
Just in case links disappear:
This is the link for finding the DM archive which currently seems elusive on the R3 website.
This is the archive of John Arkell's listening notes.