@georgeob1,
That's not really how i see the dynamics here. I venture the following.
The UK has always wanted to discuss the future relationship and the departure modalities
together, as one issue. That's because they see Brexit as the search for a new, rebooted relationship with the EU, or if you preffer, as a
reform of their present relationship so that they can benefit more from it. Hence for them there's only one issue: how to reform the present relationship.
That's not the way the 27 sees Brexit at all. They say in essence: "there cannot be a tailor-made membership in the EU: either you're in the club or you're out, the rules apply to all members equally. So let's agree with the conditions of your departure from the club (ie "Brexit"). Once this is agreed, the
other, unrelated issue of your future relationship with the club can be discussed."
The deal on the table is like a hotel bill. It says how much arrears they must pay, and then at the bottom of the bill there's this nice commercial phrase: "we remain at your service and look forward to hosting you next time!" When the client signs on that bill and pays, he can come back some other time, negotiating a special room if he wants to. If the client doesn't pay, well, he won't be welcome next time.
What the client CANNOT do, though, is conflate his checking out negotiation with a negotiation on what the rate will be next time he stays in the hotel. These are two different pieces of business that should have nothing to see with one another.