To compare SNN with Cork is ridiculous.
SNN has a limited population, drawing pax largely from the midwest and a little further afield towards Galway.
Cork alone has a population of 520,000 and draws pax from Kerry, Tipperary, Waterford and further afield.
Cork must have transatlantic ops to aid the development of the entire region. The largest foreign investment by far is from the US, especially in the IT and Pharma industries.
The current 7,000ft runway discourages airlines to begin such services. Obvious exception being Norwegian as it will use the 737MAX. It has been said many times before but most business travel ex Cork cross the Atlantic via Heathrow.
I don`t believe the DAA have any motivation to lengthen any runway in Cork and only an independent Cork Authority would have the ambition to achieve that.
Not at all ridiculous, as both SNN and ORK does quiet well for regional airports in comparison to European context.
You speak of population yes it's big but easily for 50%+ DUB/SNN are just as easier to get to with time difference not been significant with much more suitable offerings for many.
Cork "must" have T/A ops, given it has not negatively impacted on such investment before such services are irrelevant in relation to investment.
The runway is suitable for the MAX and that will be the future aircraft size for Cork and even Shannon for the most part and 2 or 3 big US carriers have MAX's arriving in next 2-3 years (UA and AA) so if they want to fly form Cork then they will. The runway is just an "excuse". An independent Cork would have more pressing issues to deal with if independent such as cost cutting the airport into profitability. While it's claimed it's profitable day to day splitting from the daa would impact this with legacy issues.
There is nothing stopping Cork from gaining T/A ops in coming years.