Lucas is a dropped ball. It's been so long now that if Nyx does anything, it doesn't have the benefit of pacing and will feel out of place. If Lucas stays in the void, his impact on Layla is a lot less significant than the initial story would have led you to believe. I think Lucas should have been one of Ethan's goons when Zach betrays MC. Would make Ethan a more compelling villain as he is taking the effort to actually look into ways to harm the MC, forming a type of alliance with others that seek to get rid of him.
Agreed, the main difference between Erynn-Ethan and Layla-Lucas(btw does Nyx like to make her villains names match first letters?) is that Lucas never had any impact into Layla's psyche or her life, Lucas left no scars on Layla, no trauma for her to overcome... and he also hasn't bothered Layla in a loooooong time.
After the last time he stopped her in the park there's the weird hoodie theft that we don't even know if it was actually him(and rich girl Layla just bought another one with minimum fuzz, literally no effect

).
The Layla relationship grew without any concerns about Lucas, there's some mentions of "think about what happened last time" from Elena in the early chapters but it got forgotten fast and things kept moving forward seamlessly.
Maybe Nyx will bring him back to get his ass kicked... could be fun.
But she really dropped the ball by completely forgetting him and not integrating his plot with the Layla relationship blossoming.