Personally I think that bitcoin will likely end up being replaced by something faster and more secure before the network is done propagating.
if this actually happens I don't forsee it happening any time soon. In the event that this newer more appears it will likely take time for BTC prices to lower and people adopt the replacement.
We should be able to see that coin coming from a mile away. The next big thing won't pop up out of nowhere. There will be extensive security and bug testing before that. No new coin will be able to take its place. Any coin should be in use for the longest time to prove it has no serious bugs that could result in major problems down the road.