You can for example convert bitcoin to LTC for free
It's called Atomic Swaps and currently Komodo is on the top of that game. LN wouldn't change much just as Raiden didn't do much for ETH. Also LN is off chain while Dash and PIVX has on chain InstantSend functionality and STEEM and Bitshares already has 3 second Tx and Verge gets it done in 5 seconds.
Also you can't exchange Bitcoins on LN. You have to deposit BTC on LN and exchange with their own currency. So you really won't be sending BTC.
You seem awfully uninformed and incompetent for a guy who claims to be investing101. Don't take me for some noob on the street. I know my stuff.