I don't think anyone could've predicted the final two members to join Luke Cage's "Mighty (Avengers (?)" team after the previously announced names of She-Hulk, Superior Spider-Man and Blue Marvel. And if you're like me, you did a double-take at the name of Power Man, an identity first utilized by Luke Cage in his early superhero days. I was thinking more along the lines of Iron Fist or Daredevil but I suppose that was a bit obvious. In looking up Power Man's (Victor Alvarez) backstory I have to say I'm intrigued enough to look forward to learning more about the character. I'm on the fence about White Tiger but I'm keeping an open mind.
The six-part Infinity series, written by Jonathan Hickman and illustrated by Jim Cheung, Jerome Opeña and Dustin Weaver, starts in August. No word yet on the creative team behind the 'Mighty' but where there's Cage there's usually Bendis.
As far as the premise is concerned, it appears most of the A-list Avengers are in space to combat the threat of Thanos and The Builders leaving Luke Cage to assume a Captain America-esque leadership role and defend a new team to combat the bad guys planet side. Cage has previously assumed such a role within New Avengers and it was well-received. Plus, it's just nice to see him in that limelight once again.

"From the battlefields of Infinity comes a new team to protect Earth! With the Avengers light-years away in space, contending with the Builders and Thanos’ marauders ransacking the Earth, who will stand in defense of mankind?"