JR Central/JR West/JR Kyushu issued a joint PR release that JR Central’s EX Shinkansen eTicket system, encompassing both EXPress Reservation and smartEX services, will be adding JR Kyushu Hakata~Kagomashima Shinkansen ticketing in spring 2022.
2022? If it’s going to take that long why bother announcing it now? I am sure that part of the reason for the long lead time is the next generation Suica card architecture (Super Suica) and FeliCa OS update coming in spring of 2021. All nine of the Suica sister transit IC cards under the Transit IC interoperability umbrella will need to switch over to the new transit card format to maintain compatibility: Suica, Toica, ICOCA, SUGOCA, Kitaca, PASMO, namaca, Hayaken, nimoca.
Right now Mobile Suica is the only transit card on mobile, and mobile offers service extras like downloadable Shinkansen eTickets. The next generation Super Suica format will likely extend mobile capability and mobile service extras to all nine cards. At the very least JR Central will have to retool the EX system for the new card architecture while maintaining compatibility with the current card architecture. It makes sense to upgrade the current EX system areas first and add Kyushu Shinkansen ticketing last.
Meanwhile, JR East is due to rollout a new eTicketing system in spring 2020.