About the example of universities, I dont advocate closing borders. I believe in self determination and industry/country to country bilateral agreements. It might be more difficult to put in place but it reflects people best interest and it is democratic. If UK universities believe its in their best interest to allow more foreign students, then they should lobby for this. There will be winnders and losers thats for sure. Not everyone would be better off. But I believe that the overall effect would be positive.
Lastly, please consider the many countries in the world who are succesful without relying on major trade agreements. Instead they have negotiated many bilateral trade agreements with other countries. These reflect their best interest, for each industry.
For the UK employees that have to compete with low cost labor... I don't think that's the case mate, its an open market, if you are good at what you are doing you are going to get valued.
Lets see what you and Boris are going to say to all those people working in Universities that are going to shut down as their main source of income are EU students.