The qualifying phrase that Johnson put in response to the PMQ question in the top Tweet might just be enough to deal with any difficulty in relation to a commitment made to the Commons over the Erasmus programme. But his wording and response was sloppy and ill thought out. You don’t say that something will continue, as in the first part of his response unless it will continue. This is just another reflection of his lack of attention to detail.
Why Britain leaving the EU should lead to closing down in Britain of a very successful academic programme is hard to say apart from Johnson wanting BREXIT to be “pure”
Another area where I think there will be an initial difficulty is the ending of the EHIC program which is going to add considerably to the costs of Britons travelling in the EU. Even the Daily Telegraph has called for an exemption on this one.
One ongoing Brexit issue for ministers is that UK citizens in Northern Ireland will continue to benefit from both programmes because of the way that Brexit operates differently across the Irish sea.