A battle with John Magnier over the 750-acre Barne Estate, a bailout for Michael Flatley in his own fight to keep his Castlehyde home, refinancing Gerry Gannon’s property portfolio, and plans for a substantial expansion of his Tipperary stud farm: The last year was a busy period for Maurice Regan, the New York-based construction magnate with substantial assets in Ireland. Now, 2025 promises to put his hospitality interests in the spotlight, with the Mercantile Hotel – the jewel in the crown of the eponymous hospitality group’s holdings in the capital – reopening this summer with a substantial multi-million-euro facelift.  In…