The biggest danger to the very slender hope that Brexit will be cancelled is that the Labour party will stop trying to exploit the situation to smuggle themselves into power and will simply act in Parliament in line with their policy.
The policy of the Labour party is to see a comprehensive Customs Union with the EU but to stay out of the single-market, thus avoiding restrictions on e.g. government investment (so that Corbyn can pour billions of taxpayers money into propping up failing private companies in order to subsidise jobs and win votes). But, anyway, they say they want a Customs Union.
Theresa May’s deal offers precisely that. A structured exit and then negotiations on a future relationship. That future relationship is not defined in the current leaving deal except that the political declaration clearly envisages some kind of a Customs Union and plans to keep the UK out of the single market. 
If Labour were to act as their policy dictates they would support Theresa May’s deal. The deal would then sail through Parliament and Brexit would be a done deal.
It is only the Labour party’s unscrupulous attempts to manipulate the situation to sneak into power that is currently blocking this outcome.
One possible resolution to the current impasse is that Labour will stitch something up with the Conservatives that changes the political declaration part of the deal that they can then present as a concession which they have won which enables them to vote for the deal.
In general terms Theresa May is correct. The current exit deal is pretty much the only one there is. – With the exception that the political declaration need not contain a commitment to end freedom of movement and stay out of the single market. But, it seems, that this point is not the sticking point in Parliament. In its three main points the exit deal is the only possible one. The UK will have to contribute some money to support projects which have been started; allowing people already in each other’s countries to stay is the only rational and humane way to solve the problem of people already living in other EU countries and the UK; given the contradictory needs of, one the one hand, the UK for a soft border in Ireland and the EU for a hard one, some kind of a ‘backstop’ is inevitable in any situation (even no-deal Brexit). A great deal of the talk in Parliament – “blocking a no deal Brexit” and talk about changing the terms of the political settlement (except possibly freedom of movement) is taking place in cloud cuckoo land. MPs (and indeed much of the leadership of the Labour party) appear to simply not grasp that the UK is not able to dictate the rules in this situation.
One of the pitiful spectacles at the moment is MPs desperately trying to shore up their ‘democratic’ credentials by saying that they must honour the public vote on Brexit – or the public will feel betrayed by politicians etc. No matter that the original vote was just 52%-48% or that current opinion polling is showing a clear shift towards staying in the EU…. If these people really believed in (representative) democracy why would they not back a second referendum? Parliament often has more than one bite at the cherry on a vote – why is this not allowed for the people?