I happened to come across the following video on YouTube of David McWilliams - as a guest on RTÉ's Prime Time back in 2014 - affirming the potential economic viability of Scottish independence:
https://www.youtube.com/watch?v=QLmveSJwQyM
The presenter David McCullagh made a point that also has relevance to the question of the potential economic viability of Irish re-unification. He posed the following to McWilliams:
"[The Scots] pay £53 billion a year in taxes, including oil taxes, and get £65 billion back, so you're starting with a £12 billion deficit..."
Of course, the north of Ireland receives a block grant or subvention of nearly the same amount as Scotland's annual budget deficit every year from Westminster - £10 billion reportedly - and re-unification sceptics or opponents often ask how the south would be able to afford that in the event of re-unification. McWilliams responded to McCullagh as follows in respect of Scotland:
"If you reduce economics to the budget deficit, you're actually putting the cart before the horse. The question is: 'How do you get there and can the Scottish economy be dynamic enough to generate revenue over the course of, let's say, ten years and to reduce its expenditure to narrow that budget deficit?' In actual fact, the budget deficit doesn't matter a lot as long as they can finance themselves and I have no doubt they can."
McWilliams went on in the clip to explain in greater detail why he believed Scotland could finance themselves, but his answer could equally be applied to a re-unified Irish economy.
Also, I think it's worth noting that the subvention received from the UK by the north of Ireland is actually a cost of partition. That doesn't mean that sum will translate into a cost of re-unification for the south in a post-unity scenario. To the contrary, a single, harmonious island economy, rather than two smaller competing economies on the one island, will be well capable of covering and surpassing the present cost of partition. Evidently, it's partition that Ireland really can't afford afford; not re-unification.
Anyway, what I find so intriguing or novel about David McWilliams' very welcome contributions to the Irish re-unification debate is that he primarily comes at it from a rationalist perspective, rather than a romantic, sentimental or cultural one, considering he isn't from what many might regard as a traditionally nationalist or republican background. His grandparents were Scottish Protestants and his wife is an east Belfast Anglican.