I heard about one playtest where if someone was going to be slid/pushed into inimical terrain they got a save to stop themselves. Whether that was a case of "50% chance of avoiding it" or "make a Dex vs DC20 check" or something else, I don't know.
I would expect that they would have something in the rules to cater for last ditch avoidance of that kind of situation. Well, I hope so anyhow