I am theoretically switching over from Reddit to Lemmy. Finding myself spending more time on Lemmy than on Reddit. Maybe it’s because I am limited to using the desktop and can’t aimlessly browse Reddit on my iPhone. Of late, the only subreddits I cared for were on sports and their matchday threads and r/watches. I found myself aimlessly browsing through r/AskReddit and asking and answering pointless questions.
I think it depends on what people make of it. Forums existed well before Reddit and Lemmy can scratch that itch. But so far a lot of the discussion has focused on Reddit and if real content doesn’t replace it then Lemmy probably will fade away.
Also, devs can make a difference. If the experience gets better both on web amd mobile then it will help.