The United States will play Germany on June 10, 2015, according to the German football association (DFB). DFB officials had spoken about this friendly so it looked likely to happen, but no date was confirmed until today when they put it on Germany's official match calendar.
Germany will host the match, with the match being played in Cologne. It will be come three days before Germany plays a Euro qualifier against Gibraltar so they should have a first choice team for the U.S. friendly. It also comes on a Women's World Cup off day, so it cannot conflict with the USWNT.
The U.S. and Germany last played at the 2014 World Cup, where Germany won, 1-0, en route to being crowned world champions. The two sides also played a friendly in Washington, D.C. in June 2013, a match the U.S. won, 4-3, against a second choice Germany squad.
If the U.S. is going to play friendlies as early as June 10 of next year, they're gearing up for a very long summer. The Gold Cup does not begin until July 7, so Jurgen Klinsmann looks set to have a training camp that will run more than a month before the tournament.
Klinsmann has made playing top level competition a priority, and Germany represents as top level as there is. Playing in Cologne will present another challenge for the U.S., and whenever Klinsmann faces off against his home country it is fun so there will be more than enough challenge and intrigue in this contest.
The U.S. Soccer Federation has yet to confirm that the match is happening at all, let alone a date. But the USSF is normally last to confirm and announce matches and while things could change, it would be unlikely for the DFB to speak prematurely so bet on this one happening.