Actually I don't think it will. Its true the comfort zone for the UK surrounding being 'in' the EU will have gone and that will have repercussions of itself. The UK will however have £39B to hand over, (which it will have to do, maybe have to pay even more than this sum for the 'ideal trade deal' ) but this time some of the 'strings' will be able to be attached by the UK, which they couldn't do before. The EU could not without tearing itself apart make any further concessions whilst the UK was part of the Union, but now proper negotiations can take place. There will of course be some more 'sabre-rattling' (both sides) about the NI/Eire border and this issue cannot be ignored because of the GFA, but again both sides will have a freedom they didn't have before especially, if Stormont is back up and running and there is a legitimate voice speaking for the whole of the province, which the last poll (EU) seems to suggest the Alliance party is making some headway. Indeed of all the new and smaller parties making a breakthrough in these EU elections, the advances of Alliance Party in NI may be the one that last longest and has most long lasting effect. There could even be an enormous boost to peace, if both sides could decided their joint economic future together, through their own Government?
Things will change once the UK is out of the EU, it will not be easy, but then again when did our politicians ever do easy?