I know predicting the future is always a challenge and full of uncertainties, but I'm still curious to see if you have any predictions of any modern books that might one day be regarded as a classic.
I personally haven't read any that falls under this category. When I think of classics like To Kill A Mockingbird, The Great Gatsby, Animal Farm, or even childrens classics like The Velveteen Rabbit, it's difficult for me to see exactly what actually made them classics. But maybe you're better at this than I am. And I would love to hear your guesses on which you think will be a classic one day.
If I had to choose one, I'd hesitantly say The Hunger Games, as it's easy to read but also has a lot to say about challenging a Communist regime. It was assigned in high school back in 2010. So at least one English teacher saw some literary value in it.
Maybe A Monster Calls by Patrick Ness for YA/MG. It has over 259k ratings on goodreads and a 4.35 rating. It deals with some serious subjects but adds in some fantastical elements. It's not overly long and so could see widespread adoption into school plans.
For an adult one, I'm going to go with a lesser known one in Apeirogon by Colum McCann. It's literary fiction about Palestinian and Jewish families dealing with a violence, trauma, and grief. It isn't for everyone, but it doesn't try to be. It currently has a 4.23 average with about 22.5k ratings at goodreads. It won some awards when it came out, and was longlisted (but not shortlisted) for the Booker when it came out in 2020.
You are confusing popularity with potential classic status. And you cannot use GR to gauge how it'll be received in the future.