So you don't think there will be any pressure from the big guns of Germany and France on the little ones to step in line? If Lithuania decide to really fuck up the revenue of the likes of BMW and Mercedes, I don't think they're going to do well out of other EU treaties/deals...
I don't think that Germany believes that BMW's revenues will ultimately be affected.
The most likely scenario for me is that, shortly after a Leave vote, Boris will demand that the EU offers the UK a free trade treaty, without any conditions such as a contribution to the EU budget or adherence to any EU directives, especially the free movement of labour. The EU will politely inform him that the only deal possible would be a Norway style arrangement. There will then be a Mexican Standoff which will last for most of the next two years. Eventually the EU will start planning to impose tariffs. At this point a vote will be taken in the House of Commons proposing that, since that Boris has failed to deliver the favourable trade deal that was promised before the referendum, a second referendum is necessary. Given that the majority of MPs are pro EU, they will seize any excuse to trigger a second referendum.
The minute that the UK votes to leave, the EU's primary objective will be to force a second referendum. They will not jeopardise that objective by agreeing a favourable trade deal.