JR Hokkaido has announced changes for the upcoming March 2022 timetable revision with the "usual stuff" aka more service reductions and station closures, and with the addition of 22 new KiHa 261-1000 Series DMU cars it means the retirement of the remaining 29 KiHa 283 DMUs is approaching as they will be replaced by the new DMUs for the remaining three Oozora round-trips.
https://www.jrhokkaido.co.jp/CM/Info/press/pdf/20210915_KO_3.pdf