The competition would be the key issue. And the field might change. Its all a bit wait and see. But the cost of diesel and tough regulations on freight drivers makes P&O Dublin to Liverpool work for a lot of companies. And the Endeavour, Norbank and Norbay carry a serious amount of freight. If you ever go on P&O Dublin to Liverpool, your car will get boxed in and trailers will make up more than 80% of the load. This year has been very good indeed for P&O. To be honest Norbank and Norbay are proving a little small in passenger & freight capacity.
I cant see Seatruck staying independent for the forcible future, an acquisition, and streamlining of the company by P&O shouldn't be ruled out. Stena's acquisition of DFDS Irish Sea, and Fleetwood back in 04, has culminated in P&O having no access to NI, other than Cairnryan / Troon - Larne. The acquisition and reconfiguration of Seatruck would provide P&O with the ability to compete with Stena.
A positive for Holyhead is that the route is shorter and I.F. could make savings in the fuel dept, and perhaps undercut P&O, but hauliers are very concerned about there own fuel costs, and driver regulations. In addition P&O Ferrymasters put a lot of work P&O Irish Sea's way, and Dublin to Liverpool is a big profit maker for P&O, and they would be keen to protect or expand there market share.