Blizzard has released update 2.08 to Overwatch on PS4 and Xbox One, and in the patch notes, you can see that Capture the Flag maps and game mode have now returned, so fans can enjoy the mode all the time, not just as a seasonal treat.
The following bug fixes have also been addressed too:
[PS4/XB1] Fixed a bug that prevented background music from playing
[PS4/XB1] Fixed a bug that prevented the Damage Amplified value from being displayed correctly
[PS4/XB1] Orisa's movement now slows slightly while firing in midair
There's also a little note at the bottom of the patch notes as well: "Much like D.Va's Fusion Cannons, Orisa's Fusion Driver is intended to slow her movement while she is firing. However, unlike D.Va, there was an issue that prevented this slow from working while firing from the air."
Are there any other seasonal modes that should become permanent?