Why is BTC no longer BTC if the PoW changes? Why are ASICs securing the blockchain? Anyone running the Bitcoin client can process transactions you don't specifically need an ASIC. Before and after all coins are minted people will fight over either the blocks or the transaction fees no matter which PoW scheme is used. If everyone would stop using their ASICs the difficulty would go down and people could process transactions with their GPU or even CPU.
ASIC are securing blockchains in order to mine coins.
Absent BTC's massive advantage in network security provided by ASICs, it becomes just another crypto, subject to much more feasible 51% attacks.
There is no silver to BTC, no copper, no aluminum.
There is only one.
That's for the market to decide, not silly greenhorn noobs like you.
If you had been around longer, you'd realize your argument is exactly the same as what the Buttcoiners say about BTC ('It's a ponzi casino funny Monopoly money scam and the US dollar will be king forever').