If you haven't yet leaped aboard the next-gen bandwagon, don't worry. Publishers aren't planning to leave the last generation behind any time soon.
Take Ubisoft, for example. Executive Lionel Raynaud told Edge that his company will continue to support the PlayStation 3 and Xbox 360 for several years to come:
"We will have games for PS3 and 360 for this year and probably the years after. We want to be able to provide games to people who are playing on these consoles. [Assassin's Creed IV: Black Flag] was the first Assassin's Creed game of this new generation but it was designed with that in mind, but I wouldn't say it was a cross-generation game, as it has features that could only be for this generation."
As for the upcoming Assassin's Creed: Unity , that may only be available for the PS4 and Xbox One, but there are rumors that a completely different entry, subtitled "Coment," will land on last-gen systems. This continued support shouldn't surprise anyone; publishers of this size require as many consumers as possible. The combined userbase for the PS3/360 is probably at around 160 million, while the combined userbase of the PS4/Xbox One is only around 10 or 11 million right now.
So, I mean…duh.