In hip and trendy companies; every company I work with (banks, insurers) are using JQuery like it is the best thing ever and never heard about React or ES5. It will live for a lot longer than Silicon Valley thinks.
I'm not in silicon valley, and I'm not in a start-up. jQuery is on the way out in all but the most archaic companies (many of the ones you mentioned are still struggling with how to maintain their Cobol code bases).
My company has a ton of legacy (significant parts of our site are in ColdFusion, for example), and jQuery is on the way out here. So... It's gotta be on the way out. :-)
