In the paper, titled Avenues for unity for the EU at 27, the Commission looks at five potential scenarios for how the EU could evolve by 2025.
The first is to 'carry on', implementing the EU's current reform agenda. By 2025 this could mean that, for example, Europeans could drive automated and connected cars but still face problems when crossing borders due to some legal and technical obstacles. Crossing borders should be straightforward, without the need to stop for checks, but reinforced security controls at transport hubs would slow travellers at the start of their journeys. E-commerce would be likely to increase as broadband becomes more available, but it would remain disproportionately expensive to have products delivered from another member state.
Scenario two foresees the 27 countries centred on the single market alone as the member states struggle to find common ground on an increasing number of policy areas. Crossing borders would become more difficult, finding a job abroad would be harder, and transferring pension rights not guaranteed, the Commission said.
Europeans would be reluctant to use connected cars, due to the absence of EU-wide rules and standards, while air quality is likely to differ across Europe for the same reason.
Some member states may be happy to do more in some areas, bringing about scenario three, the Commission said. In this scenario some member states work together on "coalitions of the willing" on areas such as defence, security or social issues. This could mean that some states work together on tackling cross-border crime, with fully interconnected databases, the Commission said. Different groupings may develop shared business law to help businesses work across borders within that group. Citizens' rights would begin to vary depending on what country they live in, it said.
Scenario four looks at 'doing less more efficiently'. The 27 EU countries could focus on the policy areas perceived to have more value, such as freeing up frequencies for cross-border communication services, or establishing a European border and coast guard service to manage all external borders. The biggest problem with this scenario is likely to be reaching agreement on what to prioritise, the Commission said.
Finally, scenario five sees member states doing much more together. Member states could decide to share more power, resources and decision-making. EU-wide rules would make some things simpler, and others more complex, the Commission said. Connected cars could travel seamlessly, but people who want to complain about a local project may struggle to reach the relevant authority, it said. There is a risk of alienating parts of society that feel the EU lacks legitimacy or has taken too much power away from national authorities, it said.
"By 2060, none of our member states will account for even 1% of the world's population – a compelling reason for sticking together to achieve more. A positive global force, Europe's prosperity will continue to depend on its openness and strong links with its partners," the Commission said.
Commission president Jean-Claude Juncker said: "60 years ago, Europe's founding fathers chose to unite the continent with the force of the law rather than with armed forces. We can be proud of what we have achieved since then. Our darkest day in 2017 will still be far brighter than any spent by our forefathers on the battlefield. As we mark the 60th anniversary of the Treaties of Rome, it is time for a united Europe of 27 to shape a vision for its future. It's time for leadership, unity and common resolve. The Commission's white paper presents a series of different paths this united EU at 27 could choose to follow. It is the start of the process, not the end, and I hope that now an honest and wide-ranging debate will take place. The form will then follow the function. We have Europe's future in our own hands."
Guy Lougher of Pinsent Masons, the law firm behind Out-Law.com said: "Scenario two, where the EU is nothing but a single market, is closest to the heart of many Brexit supporters, but it unlikely to be adopted. Scenario three, where those who want to do more do so, is probably the most likely in a post-Brexit world, perhaps combined with four, doing less but doing it more efficiently."
"Scenarios one and five are unlikely to be feasible for a variety of reasons. But of course, a Le Pen presidency in France would change things fundamentally," Lougher said.
The white paper has been created as the Commission's contribution to the Rome summit that will be held later this month, and "marks the beginning of a process for the EU27 to decide on the future of their Union". A series of debates will be held across Europe, and "reflection papers" will published by the Commission on: developing the social dimension of Europe; deepening the economic and monetary union on the basis of the five presidents' report of June 2015; harnessing globalisation; the future of Europe's defence; and, the future of EU finances.
The white paper is published the day after the UK's House of Lords backed a guaranteed rright for EU citizens to live in the UK after Brexit. The government opposes granting that right for now and has argued that it should wait until other EU countries offer reciprocal guarantees to UK citizens living abroad.
The government said it was "disappointed" by the vote and hopes to remove the amendment when the Article 50 bill returns to the House of Commons in just under a fortnight.