Commissioned by the European Parliament’s Policy Department for Citizens’ Rights and Constitutional Affairs, ACELG researchers Leonard Besselink, Bastian Michel and Katja Swider (former ACELG) published a report on what's to be expected after Brexit for the institutional set-up and political dynamics within the EU. The researchers partly used statistical modelling to inform their findings.
According to the team's findings, voting balance and bargaining power in the Council will shift in favour of larger member states.
The following (selection of) paragraphs are copied from the report, regarding the implications for the European parliament:
The composition of the Parliament of 2019–2024, based on the European Council Decision of 28 June 2018, for the first time since introduction of the present legal framework under the Lisbon Treaty conforms fully to the requirement of degressive proportionality under Article 14(2) TEU. However, postponement or a cancellation of Brexit will lead to an extension of the composition of the Parliament 2014–2019 to that of 2019–2024; this distribution infringes the Treaty requirement of degressive proportionality and cannot persist for a longer period.
The overall interinstitutional balance seems to give a relatively greater weight to large Member States in the Council, and to smaller states in the Parliament, whereas – somewhat more indirectly – the equality of Member States, in particular also the smaller states, is guaranteed in the composition of the Commission. Brexit will not upset the interinstitutional balance overall.
Take a look at the report for all of the team's findings and their recommendations. It is available as download from the European Parliament's website.