Maybe this is a mute question as it has already evolved. More specifically it has evolved to a level where it can fulfill the majority of functions available in tradfi via layer2's. The question is simply when will its use become mainstream or even the default?
For many of us Lightning already works as the default. What’s missing is awareness and merchant adoption — once UX improves and more people try it, mainstream use will follow naturally. That said, I think it will still take decades: the masses will likely move first to USDT on Lightning rather than directly to BTC. Bitcoin will be adopted as a store of value and digital gold, but a true Bitcoin standard will take much longer