As I see it there are 3 basic options.
1) Some/Any kind of soft BREXIT deal. Bound to upset hard Brexiteers and remainers alike and will perpetuate the Tory party problems. HMG and EU can't seem to agree on very much, and time is running out. An extension to negotiations past March is possibly, but seems unlikely to me unless some of the key questions are answered soon.
2) Hard BREXIT on WTO terms. Apparently little support in parliament for that, so not likely IMV.
3) Withdraw Art50 before end March and remain in. Can't see that being politically acceptable without another referendum.
I think the politicians are going to say that because no-one can decide/agree what to do, they'll throw it back to the people with another referendum. The question will be do we stay in as we are, or hard BREXIT on WTO.
If the answer is BREXIT on WTO, then that's it, we crash out at the end of March and start from scratch.
If the answer is remain, then we withdraw the Art50 notification. No-one knows for sure if this is actually possible, and if challenged the ECJ will have to decide so it'll rumble on for a few years before we know where we are.