Idk. I think likes still provide a function. Majority of posts are not worth zaps. This is what it will trend towards. The honeymoon phase of overzapping because it's just so cool technology wise will end and the volume of zaps will decrease and maybe amount per zap increase. The like function for me is what I use when I think a post is decent but simply not worth a zap. That's just how I do it. Cool thing here is that everyone has their own way of interacting with all this. Btw, I also can see the other side where likes could potentially be done away with completely and you either found enough value in the content to zap, or you didn't. That's a totally possible outcome I guess. But I don't necessarily think that having an extra function hurts anything as opposed to removing something taking away something. And the proof is in the pudding because the like button is still used quite a lot.
Discussion
People use likes, but they provide no value to the recipient. I already use nostr without them, and have been doing so for nearly 2 years now. In client apps that offer the option, I even completely remove them from my UI so not only do I never see the like button but I also never see when others like posts. It has made my social media experience so much better. But yes they exist and probably aren’t going away. I do encourage everyone to try nostr for a while without them.