Do you think Boris' trip to Brussels will be about him sealing a trade deal (conceding on a number of things to get the deal), or him coming back saying, see I tried my best?
"Sovereignty" has always been an abstract problematic concept. And it could be a big obstacle to reaching a trade agreement. The EU needs to know that a large economy on its doorstep that has free access to its economy is not undermining its market and rules. For the UK to get access to this market, there is of course something to pay. A trade-off. But if the UK has set it stall out that it can't follow any EU principles on competition or arbitration then we won't get access, and no deal on the 31st of December is quite possible.
Even the deal we are seeking is what would have been called a "hard brexit" 4 years ago. Funny old time. I think Boris will concede some ground to get it over the line. He doesn't want to be associated with thousands of lost car and food jobs (which is the inevitable outcome of no deal). Fish is symbolic. We have too much and its more important we can sell the fish to Europe, so that's an easy one to cede. We'll still have more fish than before. It just comes down to this sovereignty thing and if we can accept we will have to follow some EU rules to have access to their market.
What a chronic waste of time!