I dont think that the goal is to replace other cryptos with bitassets.
The goal is to have exchanges publish orderbooks on the Bitshares Exchange Network, to enable trading of all cryptos without trusting a centralized exchange, avoiding hacks, etc. Give users access to their own private keys, show proof of reserves, etc.
End users won't have to know that Bitshares is doing this, they will simply be using their exchange where they registered an account.