While Brexit will certainly affect the United States, it will have a major impact in Europe in so many sectors, among them trade, travel, work, and borders. Because of this, this posting will be limited to works emanating from various European think tanks. (A U.S. perspective can be read here: Economic Implications of a United Kingdom Exit from the European Union).
Bruegel examines Brexit from an economic perspective.
Carnegie Europe (Brussels) features Brexit-related works.
The Centre for European Policy Studies has a section on “Britain and the EU“.
The Centre for European Reform has “Britain & the EU“.
Chatham House contains “After Brexit: Britain’s Future”.
The European Parliamentary Research Service hosts “What Think Tanks Are Thinking” – a guide to European institutional research. The latest edition on Brexit was posted on February 17, 2017); previous studies can also be accessed.
The European Council on Foreign Relations discusses European reactions in Brexit:Responses.
The European Policy Centre has issued dozens of reports on Brexit.
The UK Parliament Library issued Brexit: a reading list of post-EU Referendum publications by Parliament and the Devolved Assemblies [definition of purpose of devolved assemblies] on March 29, 2017. This document lists hundreds of linked reports generated from the House of Lords, the House of Commons, and select committees