Due to the economic recession and continuing recessions around the world, the US economic situation is such that birth rates have dropped to historic lows. See here.
Pew Research found birth rates have not been lower since the Great Depression: As a result, certain church ministries may see long-term demographic shifts in numbers and / or volunteers.
The youngest demographic group ministries will see the first wave of that change over the next ten years. Childrens ministry across the country will be impacted by the decrease. The drop in numbers would be seen across the country in Youth Ministries 14 years out or so.
Likewise College Ministry after that would see smaller enrollments to go fishing in for Christ.
In the short term, looking at another trend, the Baby Boomer generation is retiring at fast pace. This will have another impact on the size of Senior Ministries. These age-graded ministries (that in itself is a big debate to touch on some time) will be drawing from smaller parts of the US population, no matter how successful, which will be noticeable to attenders and planners/leaders. Still the somewhat Millenials will remain a large force in ministries for the time being. The calling remains the same to reach each generation, but real shifts will be at play.