Here’s my take on the finale of CQL:
*************SPOILERS FOR EP50***************
Note: please don’t spoil yourself if you haven’t seen it because I think it’s too good to be spoiled.
After JGY dies, WWX bids WN and LSZ farewell then continues carrying on, fully expecting LWJ to follow after him and travel the world together. But when LWJ remains still, WWX turns around and realize that this isn’t the case and couldn’t help himself but tears up. LWJ is picking up the Chief Cultivator’s position to clean up after JGY and WRH, ironing out any more corruptions and reinstalling balance and order to the cultivation world.
LWJ is unable to follow WWX to become a rogue cultivator. WWX is also unable to follow LWJ back into the cultivational world because despite JGY and SS had died, too many things had happened and his name could no longer be seen as someone ordinary within the cultivational world. The cultivational world would never be at peace with his presence among them.
So they had to part ways.
So WWX, understanding the situation, smiles through his tears and tells LWJ, “You really are the righteous, most kind Hanguang-Jun.” and LWJ, in return tells him, “And you’re still the old Wei Ying.”
Then they part ways.
Timeskip. We see WWX wearing different black robes, so I assume some time had passed---probably a year or two. WWX is playing WangXian.mp3 Wuji.mp3 on top of a mountain. Suddenly he feels a presence and turns around...
.....to see LWJ smiling at him.
So, I’ll take it that LWJ picking up the Chief Cultivator’s position isn’t permanent. He intends only to fix everything that had gone wrong in the past of its two leaders, then, he either relieves his position and gave it to someone else, or installs a new system where no one person holds supreme power over the other sects. Then he goes off back into the wild to look for WWX.
And finds him through Wuji.mp3, since WWX is the only other person that knows this song. Their song.