IOTL, The Easter Rising was a short term failure that laid the ground work for the formation of the Republic of Ireland. The leaders were all executed and became martyrs of the cause of Irish freedom. What would happen if it was postponed for a year and took place after the Bolshevik Revolution in Russia? IMHO, given how red Irish nationalism can be just in general (look at Connolly) I think that the effect would be the declaration of a Socialist Republic.