A. Opportunistic encryption for http:// URIs without server authentication -- a.k.a. "TLS Relaxed" as per draft-nottingham-http2-encryption.
B. Opportunistic encryption for http:// URIs with server authentication -- the same mechanism, but not "relaxed", along with some form of downgrade protection.
C. HTTP/2 to only be used with https:// URIs on the "open" Internet. http:// URIs would continue to use HTTP/1 (and of course it would still be possible for older HTTP/1 clients to still interoperate with https:// URIs).
In subsequent discussion, there seems to be agreement that (C) is preferable to (B), since it is more straightforward; no new mechanism needs to be specified, and HSTS can be used for downgrade protection. (C) also has this advantage over (A), and furthermore provides stronger protection against active attacks. The strongest objections against (A) seemed to be about creating confusion about security and discouraging use of "full" TLS, whereas those against (C) were about limiting deployment of better security.
Keen observers have noted that we can deploy (C) and judge adoption of the new protocol, later adding (A) if neccessary. The reverse is not necessarily true.
HTTPS: Toward a Secure Internet