The decision of the UK’s Supreme Court to invalidate BoJo’s move to prorogue Parliament is a serious slap in the face for the PM. It does not, however, change the dynamics of the situation, and it isn’t obvious, at this point, what Parliament has to discuss. The October 31 EU deadline is still in place, the bogus negotiations with the EU are continuing, the act requiring BoJo to ask for an extension is law, and the issue now is whether he will comply with the law or ignore it and illegally impose a no-deal Brexit, with all of the chaos that will inevitably result.
Given his Trumpian tendencies, I’m betting on the latter, and given the issues with Corbyn and Labour, BoJo will probably win the ensuing election, anyway.