Today (assuming SW), we have Bitcoin, which allows us to build LN using a set of smart constructs such as HTLCs. But this is a result of a work of people trying to figure out how to take what Bitcoin offers and build something on top of it, what was not necessarily in the mind of the original designer. This is where we face certain technical issues that we can overcome, and it will work, but it is probably not the optimal design IF we wanted to have LN in the first place.
So, what would such a design be? Would you add new types of transactions, would you have different script opcodes, would you start of Mimblewimble?
Say you want to design an altcoin with one main goal - to have as good LN-like system as possible. Let's define LN-like system as a system of off-chain transactions with on-chain guarantees, but don't limit it very much further.
Would it be possible then to have something better than Bitcoin's LN? For example, would it be possible to avoid that channel capacity limitations (i.e. there is a total capacity of a channel and if you don't balance it, you will need to open a new one) etc.?
What are these factors in Bitcoin design that limit LN to be even better?