In Canada, they have plateau'd for about a decade. Baptisms are half of what they formerly were, and most of the current baptisms are dub kids - no new converts. So, when you consider the population increase, they are losing ground. In areas with low population growth (like Saskatchewan), we see our DC attendance drop by a couple hundred every year, and at least a couple rural congregations are disolved every year.
I predict that in developed countries, they will stagnate for a while. The current lack of converts, coupled with an aging population, will shift their demographic to become much older. This will make it even tougher to convert new ones, since the group will appear less and less vibrant, and most people change their religion when they are young. Eventually, the mortality rate will increase, and their numbers will decrease.
Overall, the waters under the old whore are drying up, but its a slow process. Don't worry about it. Being right is never settled by a show of hands, anyway.