There is no need for creating separate token and blockchain for Atomic Swaps and there are projects you can use now for swapping like AtomicDex.io, that you can download and use like non-custodial wallet/dex-exchange.
There is no leverage on AtomicDex, and each trade is actually executed as an Atomic Swap. It is a nice project for the average Joe looking to buy some Altcoin, but it’s not practical for power traders.
As it states on their website, for example:
Atomic swaps are designed such that both traders either receive the funds they desire, or nothing happens at all and both traders retain the funds they started with.
"Nothing happens at all" is exactly the problem. Your liquidity gets stuck in a canceled Atomic Swap and the market moves away from you.
This is why a penalty (claim of collateral) is needed; and this penalty can only be enacted by a system that can judge whether the TX was executed or not, on the real actual BTC or ALT chain.
Smart contracts you are proposing can often times be exploited, resulting in losing money, like we see every day on other chains like bsc with fake dex trading.
The $TRADE chain would be an actual standalone blockchain or DAG structure or what have you. But it’s a Smart Contract in the sense that it is aware of things "outside of it" and has specialized logic to interact with these.
It’s also a Smart Contract in the sense that competing instances could co-exist rather peacefully.