I think there are over 24 exchanges that offer LN but very few are as large as Kraken I think only Bitfinex would be close, the rest are either regional or bitcoin only and since it encourages withdrawing liqudity and you making less fees shitcoin casinos don't seem keen to use it

Personally, I think wallets are still lacking, I've used Muun, Breez and they were a bit clunky and crashed a few times, yet to try out the others. I think that wallets are fundamental for adoption but also things like P2P markets, where wallets can connect to so you can find liquidity easier and reduce centralisation and improve privacy

I think professional node operators are going to grow in importance as more people are onboarded and the base chain can't take more load and we have to run things like channel factories, as for % I can't image what the split will be like