"May is merely ensuring minimal remainer delay by pursuing all routes available, in parallel. "
Indeed so. If the Supreme Court rules against the government, then it would be intriguing to see, however, what happens next. Effectively, the vote last night is meaningless per se. After all, MPs have said that they agree to do X by date Y. But of course, in the normal course of events, they'd simply actually vote to do X, by Y, and they've not actually done that. There will have to be another vote. The Daily Telegraph reckons that because there is now a lost of who voted what last night, it will be very difficult for MPs to change their minds in the second vote. But I am not ao sure. This is where the amendment comes in, because by then there will have to be some sort of flesh on the bones, and it may be then that the vegetarians start complaining. So, all may go smooothly for the government, or it "may" not.
Then there's the legal position of the Scottish Parliament to consider :-)