jura2, there is much in your above post I would thoroughly agree with regarding the chaos that could ensue should there be a general election and the ERG/Tory party win following a suspension of article fifty. However, I feel that the whole Brexit situation has been so badly handled that there are no easy options remaining open to the United Kindom.
I feel that a number on this forum believe I am a strong supporter of Jeremy Corbyn, but I am not. I am a firm supporter of the policies brought in by the Labour party under Corbyns leadership. I am also a supporter of the way he has engaged with the grassroots in the broader Labour movement while those polices were brought into being. However, I believe a far more charismatic leader is required to put forward those policies to the British electorate, and i think also that is now recognised widely in the movement.
However, I do not feel that any leadership challenge is likely in the near future, and even if that should come about it would not be accepted by the wider Labour movement in the country.
Therefore, Corbyn will be the Labour leader should an election be called in the next few weeks and as stated he did very well in the last general election overturning a twenty point lead by the Tory party in the opinion polls prior to the election
However as you asked jura2, should Labour win could he negotiate a better deal for Britain on leaving the EU. I believe if that is to come about then Britain has to find a new position on a Customs agreement that does not involve the European Union having to transgress the treaties which bind its members in union. In that, I feel Britain will have to accept the free movement of labour which is now in all probability acceptable to the grassroots Labour movement on the country. However, that situation will never be acceptable to the Tory party either to the rank and file or the parliamentary party.
Indeed, the above could well be a key issue in any general election that may be called in the near future. In that, Both parties would campaign that Britain should still withdraw from the EU following the referendum, but the labour policy would entail a soft exit in full alliance with our largest trading partner.