"What May is trying to sell to the country is a worse situation than currently exists. There is no getting away from that."
Exactly correct Tilson
Unfortunately the rest of your analysis is more hope than fact.
In 4 months time, the UK is on schedule to leave the EU without any trade deal, citizens rights or indeed anything to show for two years .
The UK has no right to expect the status quo ante to continue. It cannot stay in the EU in any fashion , or have any trading or any engagement terms from 30th March next.
Unless one of the following happens.
1. It signs the Deal as offered ,and accepted by your PM.
2. The EU offers , by a unanimous decision of all remaining 27 heads of government, to allow the UK remain.
3. The ECJ makes a decision which says that the UK can unilaterally withdraw the A50 letter of intent. Of course that option, if even available would lapse on 29th March.
As very recent and public spats have shown, option 2 , is becoming less likely, .
An assumption that all will be well on 30th. March ,without one of the above is fantasy. The major advantage of the Deal, is that it does allow commerce, trade, existing agreements in the main, to continue and allows the UK remain close to the EU for possible re-integration.
Without it, planes will not take off from EU airports to UK destinations and vice versa, because there is no assurance or insurances, that they will be able to return.