Honestly, I think they will announce PS2 classic support tomorrow, the PEGI rating just went live a day earlier than expected.
Tomorrow is also the store update day so would make sense to say "we are releasing PS2 classics (in some form) on PS4 and today you can download the following".
It could be, but SCE also has conferences at TGS and PGW. They could easily use those times to promote the ''new'' feature (if it is) coming to the PS4. Launching PS2 classics/support tomorrow would be a little out of context, especially if they do not try to hype it to some extent. And sure, they wouldn't have any obligations to market and hype it and it could actually release tomorrow. Unless they hint it today on the Blog or Twitter, I'll wait for their TGS or PGW conferences for an official announcement.
Dude... don't be so pessimist! It's not like it was never hinted before. SCE did registered trademarks for similar systems (trophy support for legacy games, local emulation, etc).
http://www.eurogamer.net/articles/digitalfoundry-2014-ps1-ps2-games-heading-to-ps4
I guess the question becomes, at what pace will they release the games, and will we get a potential sizable "launch" amount, or will they start with a small amount of games?
Based of the PS3 launch of the feature, it will most likely be a modest selection of titles (likely those already available on PS3 as it). Most of times, publishers (or SCE) have to re-register the trademarks or renew the rating for these games, in certain cases due to copyrights on musics, voices or just because of the evolutive nature of the Rating Board (new factors, new conditions, etc).