This is just a very badly worded PCN. In fact the modules are not EOL, but just being updated with a revision (A version) and the firmware being updated at the same time. Because the firmware version is built in to the part number, the old part number is effectively EOL'd and replaced by a new version. So the new part numbers are:
The hardware change (A version) is a minor tweak to the load capacitors of the crystal, bringing it closer to 0ppm and so improving sensitivity in SF12.
The firmware updates fix various errata (sleep current and comms issue at low temp) and also LoRaWAN updates to spec 1.0.1
RN2903A is already back in stock and RN2483A is flowing through production now, for delivery in a couple of weeks.