Many coins and tokens are coming out every days and more than 10 are been add daily. How many of this coins and tokens are going to remain in five to ten years to come? I think many of them will become worthless in three years to come as most of them have been abandoned by the developers.
Most of the ones we will see in the future we have not seen yet today.
Do I think there will be "alt coins"? Most definitely
The common argument that we are re-living the internet days and what emerged was a single victor (TCP/IP) is a poor one, because there were not as many complex trade-offs involved with consolidating under one protocol. Different markets and different functions will require different protocols and there will only be a handful of coins (or probably only 1) that acts as the "medium of exchange" and "unit of account" between those protocols