Brexit: Where to next?

With just two and a half weeks to go until Brexit day at the time of writing, it's astonishing that all four options still remain open to the UK:

‘PLAN A’ - Leave the EU as planned on 29 March with Parliament swallowing their concerns over the plan brokered between Prime Minister Theresa May and the EU and passing it. Parliament has indicated it would pass a plan if the Backstop on the Irish border were removed but the EU is not open to renegotiation on this or any point.