I don't know if it's going to be cancelled...but with it taking this long just to start I wouldn't be surprised. Remember the delays with the first. If anything I wonder if the third movie will happen since they are taking so much time. It's going to be a decade long affair and that tends to ward off both actors and directors alike.
Even George Lucas didn't want to do the new trillogy at first because, and I quote " It takes a decade out of my life." and that's a HIGHLY SOUGHT trillogy that was done on schedule...it just makes me wonder about Trek being completed. Most of the time it's a two year turn around on a sequel or like some others even sooner because they drop the last two within 6 months of each other...which I think says how much they don't like doing lengthy trilogies.