Depends on how well things go.
At Sega Fes 2018, Sega Games Senior Producer Kagasei Shimomura announced that if the Sega Ages line performs well on Nintendo Switch, Saturn and Dreamcast games could be added to the lineup. Currently, the line will have possibly more than 15 classic Sega games, including Sonic the Hedgehog, Phantasy Star, and Alex Kidd in Miracle World, among others.
Shimomura ended the panel with this statement:
“I believe that the Nintendo Switch hardware characteristics mesh very well with classic games. Sega Ages will continue for a few years, so we hope you will support us. With enough support, I believe we could include Sega Saturn and Sega Dreamcast games as well.
The titles in the Sega Ages line will start to become available for download this Summer.