This panel from Rebirth lead directly into the Batman/Flash mini, The Button, that was released earlier this year.
Doomsday Clock, the next part of the DC/Watchmen whatever is going on, comes out later this year. >>95739999
I think it was in that same issue of Rebirth it was revealed that the Moebius Chair revealed to Batman that there isn't one, but three Jokers currently active in the world. For reference, think of them like Cesar Romero Joker, Jack Nicholson Joker and Jared Leto Joker.
I think one was revealed in an issue of Harley Quinn? War of Jokes and Riddles is currently ongoing and features Joker heavily, but I've been avoiding it, so I don't know if it's revealed anything.
Also, in future, it's best not to get your comic-book info from Wikipedia, if you're looking into current, ongoing storylines. Wikipedia only tends to be updated with complete stories, so it's about a year out of date.
I'd recommend actually reading these comics if you're interested in the story, and most modern, ongoing comics can be sourced through the Win-O-Thread and the archive of those threads. Alternatively, if you don't want to be disappointed by the Big Twos usual tactic of building up something interesting and delivering something boring, you could monitor /co/, or ask what happened when the events are over.
Most people on /co/ won't spoonfeed you like I just did, so you're gonna have to start sourcing your own info, kid.