Greenlight will never happen, simply because it's not our own IP and Greenlight doesn't allow this.
As for mods beeing ported to Source 2013 sdk, i think this will only be a question for mods which are still active.
Lots of the "finished" and abadoned mods won't see an update.
Since Valve constantly breaking stuff even on the older SDK versions, some of them are allready broken.
Especially multiplayer mods are affected by this drastically, since they require a user base.
While some things might be fixable with little workarrounds (like using the steam.inf), it's not easy to communicate that to everyone who'd like to play the mod.
So no new version means the community is dead without a chance of reviving.
On the other hand, the ones that are still active and updating their mods have to considder if it's worth the effort to update to the 2013 SDK.
Some might have not made this decission, some just don't made it public yet and some don't want to update.
And the most clever ones are waiting till valve is done with breaking stuff, fixing, braking it again and evenually fixing stuff somewhen.
