Sonic Boom continues to air with it’s second season impressing many with sharper writing and more on-point humor. But the show might get some serious episodes coming up. Discovered by Donnie (@SSF1991), the show is getting a four-part episode (hour long special) in the future called ‘Robots from the Sky’. 
From the sounds of things, this implies that Sonic and friends fight a major threat. Considering the show is part of the cannon that Rise of Lyric comes from (but it rarely ever puts much attention on that), this could be the show’s introduction to the games villain Lyric. He tries to take over the world and Sonic must work with allies & foes alike to take him down.
I’m looking forward to seeing what comes from this but please don’t take this as an announcement. This is a rumor due to no official confirmation from the creators, SEGA or Boomerang/Cartoon Network being released yet. 
UPDATE – (3/28/2017)
Official writer on Sonic Boom came out to confirm the four-part episode via tweet.

Source: Twitter