The Hardware wallet that looks like a smartphone could have following features:
i- Hot wallet that works like a savings account and could be used anytime anywhere to buy/sell products.
ii- Cold wallet, where keys can be saved in sd-card and could only be used once sd-card is inside hardware wallet.
iii- Limited connectivity with internet, the hardware wallet connects only when it needs to send transaction otherwise it stays offline all the time.
iv- No need to attach with computer or smartphone to do the transaction, as it is required in case of usb based wallets.
v- Easy to use touchscreen based interface to do the transactions.
vi- Where one can trade all kinds of ERC20 tokens or altcoins.