In fact I am still putting Boris in pole position.
He has quite a few options. First, he can delay Royal Ascent, but let's say he fails that, he can call a vote of 'no confidence' before Royal Ascent. This vote of "no confidence" is a tactical ploy and will be against his own Government.
This means that Parliament goes into recess for 14 days in order to see if another party will be able to gain the confidence of Parliament. In which case Parliament is pro-rogued and there is a snap poll on the 14th of October.
BoJo thus guarantees 2 things:
1) BREXIT on Halloween which he has no choice to deliver as he promised this to the people,
2) a snap election.
Now, there is the possibility that BoJo could get arrested. Which is very fine because the Tories will continue to campaign with BoJo as the Martyr under the eloquent Moggsy and go into coalition with BREXIT Party. They could attract approximately 50% of the vote between them.
Labor will bomb out but the Lib Democrats will achieve some success and become the main opposition party in Parliament.
There is a 50% chance the Tories and Brexit Party will win a majority and 99% chance they will come remarkably close (within 10 seats) and fall over the line with a few rogue Labor MPs who hate Corbyn.
Either way,I am tipping that BREXIT is still going to occur as BoJo would rather die in a ditch than ask the EU for an extension. I feel his vibe on that one. I would rather die myself than surrender.
He could also make some legal challenges of his own claiming that Parliament have tied his hands and therefore betrayed the National Interest as Britain has a compromised negotiating position with the EU.
The other thing BoJo can do is bribe one of the small EU countries like Malta to veto Britain's extension request which means BoJo will request an extension knowing that one of his EU partners will give Britain a get out of jail free card by vetoing Britain's arse out of the EU.
There are going to be many twists and turns here.