To celebrate the 25th anniversary for both franchises, SE is making new entries for both of them.

Square Enix Developer Teases The Next Mana And SaGa Games - Siliconera

The 10th Production Division of SE (their Mobile Unit) has been tasked with helping out in both games development now that they have finished working on Rise of Mana. While some fans may conclude they will be a mobile games due to the mobile divisions involvement,
Masaru Oyamada, the producer for Rise of Mana had discussed in an earlier interview that he wanted to make Seiken Denetsu 5 and wanted it to be a retail game instead of mobile. So perhaps we may end seeing something more interesting coming out of this news.