Assuming a government can be formed after tomorrow's vote of no confidence or the vote fails: Under the recent amendment controversially allowed by the speaker, the prime minister will be required to go back to the house with a new plan or plans for consideration. With that said the PM may still try to continue with a version of the current arrangement.
The following options exist
- No agreement will be reached and the UK will leave the EU on the 29th of March. Note this is currently the default position.
- Brexit is delayed until a deal can be reached that parliament can agree on (or for as long as the EU will allow it if they will at all).
- Parliament will pass a bill to withdraw Article 50 and the UK will remain in the EU (IMO it seems like this might happen so that brexit can be retried with more proper understanding of what is possible, etc.)
- Parliament will eventually agree to the current deal (given the scale of the defeat this may be unlikely)
In order to reach one of the above, there may well be a referendum either considering no deal brexit v the current deal, or no deal brexit v the current deal v remain. There may also be a general election if the vote of no confidence is successful.