Lighting Network is a failure, even developers said themselves. I don't know the technical difficulties that have place when developers work on building layer 2 but I know that for it to succeed, it needs to be easy to use. Setting up a lighting network is difficult if you are not a reasonable technical person. It might be easy for many of Bitcointalk members but it's way too complicated for many people too, we shouldn't forget it. If developers start building a new layer 2 solution and that solution will be as complicated as LN, then there will be no success for such a layer 2 solution, so it will be meaningless if it comes.