sidechain=altcoin
LN = offchain service.
yes they have a niche. but if you think that pushing people to the side(altcoin) or offchain service, is some how "bitcoin able to manage any possible amount of transactions" then you are not seeing reality.
you might aswell be saying
if users move funds to 'clams' altcoin and use bitgo.com multisig then bitcoin will never need to fill blocks because bitcoin is not being used.
wake up
if blocks will never be full again and people are filling an alternative chain.. then bitcoin has failed.
all because you think stupidly bitcoin would succeed by people not using bitcoin.
think rationally will you
you might as well be saying
"my marriage is a success because i stopped making love to my wife years ago, and started boning the next door neighbour and text flirting with the babysitter'