No matter what, in the end the newer coin will experience the same problem as BTC. It's the nature of blockchain. It grows larger slowing transactions. Even ETH experienced this with cryptokitties. Miners and nodes couldn't handle the load. Add more miners and modes wouldn't help because the entire blockchain has to be copied and distributed on every transaction. More nodes just worsens the problem because it floods the network with more traffic increasing the slowness.

This is what every cryptocurrency is going to face. A new trend of lighter cryptocurrencies exists where the blockchain is lighterweight, but again...it's a half measure. Eventually, the blockchain reaches a size that it's untenable.

Personally, I think ZenCash with its node design and infrastructure design is very sustainable.

At some point BTC will get so slow, that BCH will start to experience more pumping/dumping. At that point, we'll start to think

Hey...we've been here before.