I think whether Data comes back or not comes down to whether the Trek novels are going to tie-in to Countdown
(NOT Star Trek Online's timeline of events, although that includes Countdown too) or not. Several hints have been dropped so far, such as:
+Picard being offered the role of Ambassador (Paths of Disharmony)
+Spock becoming a legal resident of Romulus in 2382 (Rough Beasts of Empire)
+The use of holographic control consoles (Titan: Synthesis)
...and a few others which escape me at the moment. They're by no means definitive proof of anyhing, but it would seem the writers were told or chose to leave that possibility open. What remaining contradictions between the novelverse and CD can be easily glossed over ("Oh look, they rebuilt Shi'Kahr!") or ignored (the obvious botch of a Vulcan Praetor) should that path be chosen.