I presume this applies both to Travelcards bought from stations in Zone 9 and to those issued at stations within Zones 1-8 for travel to Zone 9?
The TfL fare table at
http://content.tfl.gov.uk/adult-fares-2019.pdf appears to suggest that paper Travelcards are still available from Zone 9 stations, but presumably that hasn't been updated yet.
As this fare table shows Travelcard prices for Zones 1-7 and 1-8 as being the same as for 1-9 (£13.90 off-peak, £23.50 Anytime) I presume this means that paper Travelcards are no longer available from Zone 7 and Zone 8 stations.
I guess this means that passengers from Zone 7, 8 and 9 stations can no longer buy a paper Travelcard, but passengers from stations outside the Travelcard area or from within Zones 1-6 still can at least for now.