Britain got a new prime minister Wednesday — but the country's post-European Union future remains uncertain. Indeed, prolonged delays are likely in implementing the voters' decision to leave the EU.

The first uncertainty is the date when exit negotiations will start. The process should be completed within two years of invoking Article 50 of the Treaty of Lisbon; but the new prime minister, Theresa May, has already said she would not want to trigger negotiations until the end of the year.

The second uncertainty is whether the negotiations can simultaneously resolve the United Kingdom's terms of exit from the EU and its future trading arrangements with Europe's single market. While the U.K. will claim that, under Article 50, negotiators should be "taking into account the framework of future relationships," the EU trade negotiator is insisting that future arrangements can be discussed only after Britain leaves.