Expansion and contraction occurs in all new markets. I'm sure a few will struggle and fail to get a following of devs and users. However, I fully expect a future that has millions of currencies.
Much like the conversation - Do we need 1,000s blogs? Does every person need a blog on the internet? And now, we have millions of interesting ideas being shared and read. Soon, we'll have many pockets of value created, maintained, and shared.