Via Radiotimes.com:

Star Wars and the yellow text crawling across the screen go hand in hand. It’s how Star Wars films always begin. Everyone knows that.
But it looks like the iconic opening is not set in stone for Rogue One: a Star Wars Story, with news that the spin-off may well go its own way.
“The crawl and some of those elements live so specifically within the ‘saga’ films that we are having a lot of discussion about what will define the [standalone] Star Wars stories separate and apart from the saga films. So we’re right in the middle of talking about that,” Lucasfilm president Kathleen Kennedy told Entertainment Weekly.
It won’t be the first time. The animated Star Wars: The Clone Wars is so far the only theatrically released film to go without the crawl, opting for a voiceover instead.
On the one hand it makes sense for a new opening to be used here. It’s a spin-off and is literally called the ‘rogue one’. Why not change things up? On the other hand, it is a staple of the franchise for many fans. Plus, given its setting – between the events of Revenge of the Sith and A New Hope – it might be useful to be given some more context at the beginning.