An end to the backstop that we asked for in the first place, and that wouldn't be a backstop at all if it's time-limited? They're laughing at us.
You blithely say that if the EU don't shift, it's WTO on 29th March, as if WTO is something different than No Deal. As I've already pointed out, No Deal won't happen on 29th March because there will be an extension to Article 50. It could still happen at the end of the extension of course, but it will be encumbent upon us to come up with something new to avoid it, permanent CU membership being the obvious answer. WTO doesn't solve the Irish border issue.