This may seem contraversial, but another way of improving domestic soccer would be to have Ireland join with some other small western European countries to have a combined top division.
UEFA are the biggest barrier to this - have a thing about domestic leagues having to be based in 1 country only. This perpetuates the strenght of English, Spanish & Italian football and is biased against small and medium sized countries. If you got all the small countries in Europe and aggregated them into bigger leagues, then these bigger leagues could be a good as the Premiership. Champions League could be the top teams in each of these bigger leagues. The classic example is why isnt there a Scandanavian League instead of leagues in the individual nordic countries?
An appropriate league for us might be with Northern Ireland, Scotland, Belgium, Luxembourg and Netherlands with each getting a pro-rata number of teams in a 20 team league. Would mean Ireland would have 2-3 genuinely world class teams.
I dont think FIFA would have any objections, they've already done this in Australia/New Zealand.
With modern cheap air travel, it should be possible. A sample "Atlantic League" could be (for demonstration purposes - I may be wrong on who the best teams are in each country).
Netherlands: Ajax, PSV, Rotterdam, Utrecht, Vitesse Arnham, Feyanoord.
Belgium: Anderlecht, Brugges, S. Liege, Mechelen,
Luxembourg: 1 team based in Luxembourg city.
Scotland: Celtic, Rangers, Hearts, Aberdeen, Dundee Utd.
N. Ireland: Linfield.
Ireland: 2 x Dublin teams plus Cork City.