Not sure why some people are calling it dead already.
1. While he's a core dev, he's definitely not the only dev
2. Lightning has never been perfect. But while it technically works, it's simply not ready yet. There's a reason why I never recommended it to normies yet as of yet. But, let's not forget that —
3. Software can be improved
Exactly.
Why even speculate about that when 1 person is leaving the team.
Sure lightning didn't have as much success as it once was hoping for, after all it started very promising. I also never really used it, just tried it out for a split second. The idea behind it is great but it still needs a lot of improvement to be done in the near future fur it to actually succeed.