Good article in the Guardian about it. Emphasises how it played into the Cameroonian position, and syas that the EU TTIP deal is still far from completion.
"Cameron could not have asked for more from Obama's Brexit warning
The US president issued a dramatic warning about the UK’s trade deal prospects. The only thing missing was a ‘better off in’ poster
...
That said, in practice Obama’s trade deal warning has some problems. The Transatlantic Trade and Investment Partnership (TTIP) between the EU and the US is still a long way from completion. The US trade representative, Michael Froman, has been in Britain this week to discuss how many chapters are yet to be agreed. There is almost no chance that this particular trade deal will be completed during the Obama presidency.
There is also an argument voiced on the left in the UK and much more widely in Germany that the TTIP is damaging – a deal for big business and not consumers. In his pro-Europe speech last week Jeremy Corbyn, the Labour leader, went out of his way to say he opposed TTIP and that it would have to be recast.
In Germany, where Obama travels next, more than 150,000 people marched in Berlin against TTIP last October. A poll by YouGov released this week found only 17% of Germans think TTIP is good for Germany, down from 55% two years ago. One in three Germans are against the agreement entirely. "
www.theguardian.com/politics/2016/apr/22/cameron-could-not-have-asked-for-more-from-obamas-brexit-warning
I would put money on it that if we leave the EU, there will be a UK_US free trade deal years before there is an EU one, because our teams of negotiators will pass everything that the US asks for without a murmur and the people will be told by our metropolitan elite that that was in our interest.