Recently, there has been some speculation into what will happen to the Catholic Church, once the priest shortage hits. Right now, the priest shortage is bad, but it's only going to get worse when our elderly priests begin dying. Currently, the average age of a priest in the United States is 63. Statistics say that by 2020, half of the priests who work now will be eligible for retirement.
A lot of places are trying the "one priest is in charge of multiple churches" technique. That can work, but it's not an ideal solution. You're going to run into problems, especially with masses that must be at a specific time. If I was a priest in that situation, I think the time constraints would force me to do some things from the older mass. For example, have a one-line introit in place of an opening song, say the prayers in the (shorter) Latin language, and use a communion rail, since that's at least 33% faster than having a bunch of Eucharistic ministers. Also, only the priest gets to drink the wine, because that's also 33% faster than having a bunch of Eucharistic ministers.
One person suggested going back to "each church is responsible for their own priest". That is, if no one from your church has become a priest in the past 30 years, your church does not get a priest. I think that would be an interesting solution, but it's hard to imagine a scenario where the number of priests and churches line up perfectly.
Either way, I think the issue is somewhat moot, for the United States. If the statistics are right, the priest shortage is going to hit Ireland and Europe about ten years before it hits us. Let's see how they handle it, first.