The fact is that more people are watching football. When started watching City, they were getting crowds of anything from 8,000+ to 15,000 in a 63,000 capacity stadium in the Second Tier. At that time Stockport were attracting less than 3,000 for home matches.
Now City are getting 55,000 (soon rising to 60,000+) while County are getting 10,000. For all Premier League matches, and many lower leagues games, the ground capacity poses the limit on attendances.
It is nonsense (and insulting) to suggest that those going to lower league matches are doing so purely because of PL prices. If there are people switching it is more likely to be down to unavailability of tickets than prices.