Ignoring the fucking shit glowing visor and whatnot, Darren Arafonsky is helming this new project (Robo's back yeeeee!) but after initial rumours of it being a sequel, it actually may be a reboot (boooo!)
Quotation on the matter:
Asked where in the series the fourth film would fall, whether it would come after the first, second or third films in the series' internal universe, Fischer and Medavoy were adamant that it would stand on its own, apart from the character's earlier incarnations.
"None of [the earlier films are] going to be canonical, as a matter of fact," Fischer revealed. "I wouldn't say it's a direct sequel."
"Definitely not a sequel," Medavoy added, saying he preferred the term "reimagining."
*but it seems they're going for an R-rating, which is good news at least.