LN as in Lightning in general instead of a specific implementation?

In my eyes nothing, the userfriendly software on top to manage nodes and prevent force closures need to improve but that's not part of LN. Base layer needs to eliminate the dominance of one centralized implementation (Core-Bitcoin) but that's not part of LN. The userbase needs to grow to get a stronger and more resilient network but that's not part of LN.

Overall I can't think of anything that's only specific to LN.