I like Rust, but IMO no language will ever again be Java-level popular (not even Java!) in the same way that e.g. there will never again be a band as big as the Beatles. Technological contexts have changed such that niche languages can now successfully thrive and counteract the lower switching cost that comes with a monoculture; while certain languages "in the middle" will still dominate, the long tail will get longer and subsequently lower any dominant language's market cap.