I do not live in any of the areas listed but we have many empty churches around here. I see few young people in church. Our church is not fuddy-duddy at all but it still has problems attracting younger people. My family changed churches a few years ago so their children could have more interaction with kids while learning. We attend the same church now. The members support the youth and we do have an active youth program, just not enough of the 25-50 year olds who have money. We have the older on fixed incomes. We are not an unusual church. What is unusual is that most are retired professionals with large pensions. For now our church is safe. As these members die off we do not have enough coming up to replace them.
Churches are expensive to heat. Most are not energy efficient.
The other thing I see here is the growing of small non-denominational churches. There is no hierarchy, no having things run through the denomination center. In our church we send money to this center. The non-denom. do not have this expense. They are often in storefronts rather than in stand alone buildings with parking, etc.
I don't think Christianity is dying but our old vision of what a church is could be. We need to either revisit our vision or change with the times.