game director Jeff Kaplan on the Battle.Net forums today saying at least three new standard maps would "likely" release sometime this year. The thread was , who questioned whether or not the trend set of two new maps per year—Eichenwald and Oasis, so far—was enough to sustain the game as it approaches its first anniversary.
"We currently have 3 maps in development," Kaplan said in , "all past the initial playtesting phase that are 'standard' maps (Quick Play/Competitive). While something could always change, all 3 of those are looking likely for a release this year." So while we don't know what type of maps those might be, they'll all seemingly be put into the regular rotation sometime in the next seven months.
Kaplan continue by saying they "also have 3 non-standard maps in development (these won't go in QP/Comp)." It's not entirely clear what this means, but it's easy to assume it could refer to unique maps made for events, similar to the event last year—though all the events since then have just used modified versions of current maps. The non-standard maps could be variants like that as well.
Kaplan finished by saying the Overwatch team "also have a few other experiments going on," as I imagine they almost certainly always do. We'll keep an eye out for when these maps get officially announced, but it seems this year will have a higher concentration of new locations to visit than Overwatch has seen in the past.