This is also true. Nor is there any plan for international air travel, the Irish border, Gibraltar, nuclear material including radioisotopes, road freight, food export, farm subsidy replacement, or the 3m European residents of the UK or UK residents of the EU. There will be only one time in the UK: "too late".

Staying wouldn't have required them to do anything different.

AFAIK staying (i.e. cancelling article 50) needs approval of all EU members. So it's quite unlikely to happen.

Yes - the do-nothing situation here is that the UK leaves the EU, it’s international agreements with the EU, and almost all of it’s worldwide international agreements, which are negotiated through the EU. For those who’ve read the term but don’t know what it means, this is “No Deal”.

With regards to cancelling article 50 - there is no precedent for it, but there was no precedent for using it either. It’s considered an ornament. A lawyer who wrote it insists it should be revocable - but nowhere in law says it is revocable. Or irrevocable for that matter. So those who want to reverse it should plan on getting total unanimity from EU27+U.K. because anything else might not be enough.