These are very relevant questions to which I have no great insight however it looks like there will be some reduction in Ireland-UK traffic and therefore less ships heading across the Irish Sea. Some of those unused ships may be suitable for the long sea crossing to France but I suspect not all.
In the short term it will be all about freight but as societies open up [and the UK may be ahead of Ireland] passengers demand will rise. Also as we head into Q2/Q3 duty free may become a factor, will booze cruises to Holyhead return? One other point what about the IF fast service? Has that gone for good?
One thing is certain the times are a changing.