The number of TDs is set down in the constitution at 1 for every 30,000 people, that's why we have so many. The only way to change that is to change the constitution. In the UK there is an MP for every 100,000 people.
In the case of Councillors it works out at about 1 for every 4,500 to 5,000 of population.
The only way to properly examine the issue is to decide where we want power to lie and how power is devolved out to Local or Regional Authorities. That will require major work on the Constitution and I don't see that happening any time soon. However, the prospect of a United Ireland will require major examination of our public representation and how it is managed and established.