"Let's Push Things Forwards"

Today the IRA took a step that seemed unimaginable to me as a teenager. What happens next? The DUP have predictably downplayed this, and their mandate is still, frankly, scary. But for how long can they refuse a dialogue with Sinn Fein now before the 2 governments write them out of Northern Irish politics. I expected them to say pretty much what they have said today, but surely now any moral high ground they wanted to claim has been cut from under their feet? At the same time, a united Ireland doesn't seem a realistic prospect in the visible future. Assuming Sinn Fein grasp this, what do they want from the political process and how will they be able to sell this move to militant Republicans, or how much progress do they need how quickly before cracks start to show? For me this is only the beginning of a resolution to the Troubles, but is there some light at the end of the tunnel here?