from what I can tell lightning isn't/won't be Bitcoin exclusive and it's also going to incorporate litecoin. Ethereum has its own version raiden which should be able to speak to lightning so this is where it really gets interesting.
I think it makes Bitcoin far more efficient especially for DE-FI, if they can crack lightning pools, then I see no reason why site like HODL HODL can't do lightning multi-sig loans the way it does main-chain loans.
The pieces are all fragmented right now, but I see it all coming together and its going to be awesome. Hence my reason for staking sats and learning about lightning
Oh wow that sounds pretty cool if it integrates ETH and other chains too - wei transactions without the fees could also be game changing!
You're right about the De-Fi side of it, think that would make sites like HODL HODL a great place for those with knowledge on DeFi to play around with!