Mark Nottingham, who's chairing the working group, and has been at this stuff for a while, has a blog post about this: https://www.mnot.net/blog/2014/01/04/strengthening_http_a_pe...
Chrome and Firefox will still insist on TLS for HTTP/2. In addition, the HTTP/2 spec does mandate that any implementation must support TLS 1.2 and up, and it must support forward secret ciphersuites.