Bitcoin just started, I will certainly still support Bitcoin. See the development of bitcoin pricing is becoming stronger I think bitcoin will last up to 100 years is possible. But the future is unpredictable, all is just guessing
The only thing we can do is speculate about the future of bitcoins as no one can give an clear picture of what will happen to bitcoins in future and I think its a waste of time to keep on thinking what will happen to bitcoins after 100 years.