LN, in my opinion, is only a micro-transaction/micropayment solution. It is the same thing like a prepaid card - only that the prepaid card issuer cannot run away with your money. At least not that easy.

So I consider LN an improvement to centralized wallet-to-wallet transactions (e.g. coinbase wallet to other coinbase wallet).

The good thing is that we have plenty of altcoins that can test different scenarios between the extremes "LN for nearly all transactions" and "only on-chain transactions".

Apart from that, Segwit would also facilitate Atomic Cross Chain transfers - no more shady exchanges (Cryptsy!) needed. That would immensely benefit all altcoins out there.

PS: Litecoin adoption seems to have stalled a bit but is pretty good (17-19%) as it's only the second activation period and there is plenty of time still.