A very small hope. Brexit—take back control by the improbably-named Jolyon Maugham, suggests that a court ruling could be achieved which would ensure that we can back out of Brexit at the last moment:

The effects of an Article 50 notification are not fully understood—and not only because May is still peddling a blind bargain, a Brexit pig-in-a-poke. We do know that, should we ask and the other 27 member states agree, we could remain. But it is brave to assume that two years of exposure to the negotiating skills of Boris Johnson, Liam Fox and David Davis will not generate even one hold-out. [...] The preponderance of legal opinion is that we could, after all, decide to remain. That we could, having notified, withdraw that notification. But, given the magnitude of the issue, our parliament must know more than what the answer probably is. It must know what it actually is.
[...]
only the court to which we all subscribe can give an answer: the European Court in Luxembourg.

He/she (I’m guessing “he,” from the writing style) says:

But a case which—along with Green Party co-leader Jonathan Bartley, Steven Agnew, a Green member of the Northern Irish Assembly and Keith Taylor, a Green MEP—I am bringing in the Dublin High Court seeks to give us the power to travel back if we need it.

And he explains that:

We access it via a national court. And it can’t be one of ours. One of the complaints in the Dublin case is that the other 27 have breached the Treaty by excluding us from Council meetings before we’ve notified under Article 50. And that complaint can only be made by a court in one of those 27. The Irish court is the natural choice

Which all seems fair. The idea seems to be that the European Court of Justice could rule definitively that we could revoke our triggering of Article 50 at the end of the two-year negotiating period. And if the deal is bad, or especially if there isn’t one, parliament is likely to call another referendum in those circumstances, wherein we’ll know exactly what we’re voting for, and get it right this time.

A small hope, like I say. And it doesn’t protect us from the damage that’s being inflicted in the meantime.

But a small hope is better than none at all.