So, current agreement was non-binding on parliament, and can be ignored? Well, remember what else was non-binding on parliament? Freaking Brexit referendum! For which there would surely not be support any more.
But, then there's this:
BTW, this Jacob guy (for US-ians watching in amusement) stands to gain a substantial amount of money if the UK crashes out of EU without a deal. He has a company that bet against the British pound. He's also a member of the UK government.