You need to read that article again. His reference to continuing to be part of a free trade agreement is said to come from Germany's BDI. He then mentions a points based immigration system in the SAME ARTICLE.
I don't know what the future will hold, but if you think that everyone who voted leave is going to have a breakdown due to that article then you are grossly mistaken.
It's possible, yes, of course it is, but it is incredibly unlikely because access to the EU free trade area requires ratification from all 27 remaining states. I've said it several times already, but I'll say it again, whilst Germany et al might do a lot of trade with Britain, there are many among those 27 that do very little.
For countries such as Romania and Poland, the free movement of people with Britain is far more valuable than a free trade agreement as they simply don't trade much with us (relative to other EU nations), so it's unlikely that they would agree to any arrangement whereby free movement is off the table.
To repeat, it takes one nation to scupper a deal. Just one. Now Boris may be some kind of negotiating wizard, but I'd say the odds that he will convince the EU to overlook something that is enshrined in its constitution as a founding principle is rather unlikely.

