This just means that transaction format is similar and the UTXO set has been copied. I don't see how, in practice, Bitcoin Cash is different than other altcoins. It's similarly easy for merchants/services to accept other altcoins. The BTC network has certainly not been cloned; BTC users carrying on normally can't see activity on the BCH network. It's incompatible, ignored by their nodes.
The only thing that separates Bitcoin Cash (or Segwit2x) from other altcoins is marketing. The fact is that any hard fork is an altcoin. Fair enough, maybe we will all be using some altcoin in the future rather than Bitcoin.
Network activity, demand. Just like any other altcoin.
There are wealthy interests in the Bitcoin space with a lot of money to market their BTC fork and spam/attack the BTC network. And they also have a lot of BTC to dump. I don't think they'll prevail, but they (Bitmain, Roger Ver, etc.) are nothing to sneeze at.
Yes, I agree with your definition that any hard fork is an alt. And further that BCH is an alt. I would like for it to prove to be just like every other alt, but I'm not convinced it is. Let me refine a statement though that you pointed out, the network isn't a clone (since network is made up by the participants and by defintion has to be different), but the network infrastructure is a clone at the split point. The thing that differentiates BCH from just another alt is that anyone currently transacting in BTC already has funds in BCH and switching or adding BCH requires less friction than a substantially different blockchain.
As for you answering my question: what's preventing you from switching to BCH, you responded then network and demand. That's partially my point. If the BTC network once again proves unable to scale and handle the capacity crunch, then you don't have even that, and if inertia is the only thing keeping BTC the larger ecosystem, I think you'll see parity or eventually BCH emerge as the winner if BTC can't get its act together.