According to the Japanese blog
Esuteru, Sega has filed a new trademark with the Japanese Patent Office for something called
Valkyria of the Blue Revolution. The filing was not specific beyond the name and the classification (it's a video game). Since the Japanese name for Valkyria Chronicles was
Valkyria of the Battlefield, the names are similar enough that it could mean Sega is planning to revive the beloved (yet unappreciated) strategy series.
The original Valkyria Chronicles came out in 2008 for the PS3 to wide critical acclaim, but didn't sell very well. Its sequels were banished to the PSP, and apparently didn't sell well there either (the second game made it to America in 2010, but the third -- released in Japan in 2011 -- did not).
If Sega is now willing to give the Valkyria series another chance, the only question is where? A freemium phone game would be a big slap in the face, given the only people who care about the brand vastly prefer console gaming. Hopefully the company has the sense to realize this, and is preparing
Valkyria of the Blue Revolution for PS4 (I'd also suggest Vita if the Vita was alive).