What if Harrisburg passed a law stating that only political jurisdictions with 5000 people or more will be recognized as legal municipalities after 2015?
78% of PA’s municipalities have less than 5000 people. 5000 people is a very small tax base, but that would still manage to reduce the number of municipalities by 1,998. There are 2,562 in total.
The advantage of doing it this way would be that it compels action – the potential loss of state aid would be hanging over the process – but it leaves the exact size of towns up to the local governments. Maybe some near-in boroughs would choose to merge with core cities, and maybe others would choose to align with townships.
Local governments would choose the political configuration that best suits them, but whatever the results, you’d at least ensure that local governments have tax bases large enough to support full-time professional public services.