Still be one official language of two EU countries.

Ireland has Irish, and Malta has Maltese; both non-Germanic languages, very different from English.

Oddly, Brexit can solidify the use of English as a common language in the EU, since its general use can now be considered not to give a political advantage to the UK.

(Of course, English is already a default de-facto common language in the EU, but some larger countries can be rather protective of their national language in an official capacity.)

As former Swiss resident, and fluent speaker of three of the national languages, seeing Swiss speak among themselves in English was always kind of ironic. :)

Irish in Ireland is adminstratively mandated, but as a language it is on life support.

There's a particularly pernicious habit here (Ireland) of bleating about the requirement for bilingual versions (Irish always first) of official texts. It serves only to bolster the self-importance of gaeilgoirs (Irish speakers) who have voluntarily made the language part of their identity.

Of course, it is impossible to refute the arguments they put forward for the cultural value of the language... so it goes on.