On 22 October, McCann Fitzgerald published an article saying that it is essential for businesses to consider Irish company law implications of Brexit for certain corporate structures such as those UK entities with Irish businesses and, Irish entities with UK directors or a UK holding company. It says that if businesses have not already done so, in reviewing their corporate structures, they should ask whether they will need to establish a new legal presence or business presence elsewhere in the EU, whether by way of incorporation, branch or by a strategic merger or acquisition.
https://www.mccannfitzgerald.com/knowledge/brexit/Be-Brexit-Ready-Irish-Corporate-Structures
I had omitted the following link (as it did not seem to generate much interest!), but it seemed time to add it again and say that, if you would like to make a (polite) gesture and help me with my removal and computer costs, I have a page at https://www.buymeacoffee.com/KoIvM842y