Re: Three things you can do about this Brexit nonsense
"Once Article 50 is triggered there are only two outcomes, we leave with a deal in place, or we leave without one."
The third option seems to be to retract Article 50
“there is nothing in Article 50 itself one way or another; it does not say
that you can retract or, once invoked, that you cannot retract. So it is left
to the lawyers to have those enjoyable disputes to sort it out.”
http://www.publications.parliament.uk/pa/ld201617/ldselect/ldconst/44/44.pdf
http://www.publications.parliament.uk/pa/ld201516/ldselect/ldeucom/138/13804.htm#_idTextAnchor008
So it's probably down to the lawyers.