I agree with you completely. Cookies are an older technology and is well supported in all kinds of browser. Plus it does the client side of session management for you(sending the tokens on every request). Localstorage is newer technology and might not be feasible in all situations. Plus JS+XHR are also not available to all kinds of users. (People using Tor, NoScript etc).

Also, I don't see the advantage of storing session/auth tokens in localstorage over cookies. Both are stored in plain text, and can be read if somehow it is obtained. Also, using localstorage means writing your own client-side implementation of doing the session management.

I also don't see the advantage of using session tokens in URLs. Anyway cookies are included as part of header of the HTTP request, you don't have to have your application send session trackers. I think both are functionally same and the tokens in URLs just does not look good!

And public/private key-based signing system is still not there yet, unless we simplify some UX issues about having private/public keys for every user, we are not getting there.

So, it looks like, to me, there is no really effective alternative for doing sessions apart from cookies (even in HTTP/2)?!