I think that firstly, EFT needs to become more mainstream and not have as much of a "cult-like" following, which in my opinion has already happened a bit as the game has gotten bigger and better. This is because every other classic map in FPS history came from hugely popular games like COD, CSGO, and TF2.
Secondly, is the map good enough/iconic enough? It certainly is the most "Tarkov-ey" feeling map in my opinion, but it does have its flaws. It wasn't the first map designed AFAIK, Factory was, but it certainly feels like an OG map with some iconic spots like Dorms that make it a great place for some legendary moments.
In your guys opinion, will Customs, or really any map in EFT, ever be seen alongside the FPS greats like Dust 2, Shipment, and other maps in super popular FPS games, or is EFT being a different style of FPS/more hardcore potentially making it a bit less mainstream?