Okay forget the any old deal. This deal, as I see it there are 4 opinions on it, The government who tell us it's a great deal. the EU who say they have got a very good deal, the leave supporters who.like you say it's a very good deal and delivers what they want, then the remain voters like myself who think it's worse than we had but far better than no deal. So nobody thinks 'no deal is better than this deal', except mabe a few loonies at the fringes.
So when new governments, or this one, negotiate new deals, or change this deal, and they will at some point,in fact services are still to be done, then the walk away is to remain on this current deal. That is why the old walk away of no deal is no longer viable, because no one thinks it's more viable than what we now have. It's possible yes, but not viable.
You really don't think when / if we change government they won't want changes to the deal. Unless you think we will have Conservative majorities in perpetuity, Don't forget we will have divergence across the UK of how close we are tied to EU rules. N.Ireland have theirs with ties to S.M . Scotland are in the process of tying Scottish law to EU rules in the future.