How soon will the 'ice apocalypse' come?

An emotive article on the 'ice apocalypse' by Eric Holthaus describes a terrifying vision of catastrophic sea level rise this century caused by climate change and the collapse of the Antarctic ice sheet. But how likely is this - and how soon could such a future be here?

I've been gripped by the story of Antarctic 'ice cliff instability' ever since Rob DeConto and Dave Pollard published their controversial predictions last year. They suggested disintegration of ice shelves caused by global warming could leave behind coastal ice cliffs so tall they would be unstable, crumbling endlessly into the ocean and causing rapid, sustained sea level rise.

I'm glad Eric Holthaus is writing about an impact of climate change that is both certain (seas will rise around the world, no matter what we do) and incredibly important (we must adapt). I'm sympathetic to his concerns about the future. But I think his article is too pessimistic: that it overstates the possibility of disaster. Too soon, too certain.