Splitting Dublin into 4 is a no brainer but until Central GAA and the other 31 Counties get some backbone and push it through we won't be seeing it.
Rural depopukation in the BMW ( and most other Counties) has been ongoing since 1845 
Solves the problem of Dublin’s advantages but causes or doesn’t solve other problems
It is a not a valid criticism of a solution to a problem to say that it doesn't solve other problems.
What other problems does it cause?
One of your four counties has 14 odd clubs, a second 5.
Time for Volunteers to work harder 
And how many playing members would those clubs have?
The county of Dun Laoighre Rathdown has 218,000 souls. 7th most populous county in the land. More than Limerick, Armagh, Kerry, Mayo, Tipp, Kilkenny and so on.
It has 9 GAA clubs out of the 134 in Dublin. You have Crokes, a huge club that traditionally was the whole catchment area. The original superclub. You have Cuala, a small club set up in the 70s having the GDP of a small African nation pumped in to give the real Dublin money a club. We can discuss bang for buck, but it has worked.
Then you have Olafs and Balinteer ST Johns, mid sized, decent, clubs.
The rest are 9th division public park stuff.
So you have 3 senior hurling and 4 football.
By contrast, there are 27 soccer clubs, 2 are semi pro.
How the fock does that translate to a county setup?