If we're going to start doing this to all the ridiculous predictions stated with Dunning–Kruger-like authority here, this thread is going to be become hilarious.
(Not to say that applies to Mashton, who I'm sure was just reporting what he had been told)
Sadly, they won't.
(Source: I am married to a public law QC who works with many public law QCs in a chambers regarded as on of the best public law chambers in the world.
None of them think that the SC will uphold it.)
It doesn't rule it out, but I am certainly not hopeful.