Tories have two obvious paths forward to them at this point.
One is as @caringcarer suggested - Boris brings back some sort of variation of the original Withdrawal Agreement with sufficient wiggle room to get the die hards and the DUP on board, it passes, and we're out into a transition phase where we're paying members with none of the clout in all but name for the next couple of years.
The other possibility I see is that Boris & Co do their damnedest to demonstrate they tried to get out but were stymied at every turn by Remainers in parliament and in the courts. They request a brief extension, and follow it up with a general election.
They then set up a full on proxy-referendum general election, with a very seductive "Tell Them Again" narrative pitting ordinary people against "Remainer Elites", with the clear aim to secure enough northern labour leavers to form a majority.
In all honesty, I can see it working, particularly when the alternative is the absolutely awful Corbyn.