Update July 20, 2018: Yup, Batman is indeed going back to his classic book, as confirmed Friday at Comic-Con International: San Diego.
Here's an updated look at Tony Daniel's Batman #55 cover and another unspecified image from Batman artist Lee Weeks.
Original story June 18 2018: DC Comics' solicited cover for September's Batman #55 shows the Caped Crusader in a costume much more reminiscent of his classic look than the Greg Capullo-designed suit he's sported since the onset of "Rebirth."
TLDR... Batman has his trunks back.
In the #55 cover by Tony Daniel, he's wearing a suit with a plain black Bat-symbol and trunks, as opposed to Capullo's design which incorporates a yellow border around Batman's symbol and lacks the trunks. A similar suit, with the more classic logo, appears on the cover of Heroes In Crisis #1.
However, the cover could constitute a flashback of sorts, with the solicitation for the preceding issue, Batman #54, mentioning a "stroll down memory lane" with Nightwing, who is also pictured on the #55 cover.
There's also the added wrinkle of Batman's look in the current Doomsday Clock limited series, which is set in the future of the DC Universe. In that story, Batman has yet another costume - one with the yellow oval on around Batman's emblem restored.
Superman returned to his classic costume (and trunks) with April's Action Comics #1000. At the current twice-monthly rate of Detective Comics, DC will reach #1000 in March 2019.