I’m not an expert in UK constitutional law, but it is my understanding that the decision to require parliamentary action prior to the invocation of Article 50 is legally sound, and is likely to be sustained. That raises some serious questions about what the government, and the opposition, should do next.
The Prime Minister has resisted calling an election even though she would be likely to win it with a substantially enlarged majority because she wants to avoid civil war within her party. There is undoubtedly a majority against Brexit in Parliament today. Would the opposition and the pro-EU members of the Conservative Party cooperate to bring down the government and force an election under these circumstances? My guess is that the answer is no, but we will likely find out in a few months.