I won't write all my predictions for the Smash Direct in this thread. I'll reduce my list to the character-specific ones.
A Smash Direct at this point could mean an earlier release. What's the matter with an earlier release? Well, we have still many veterans who need to be confirmed and maybe because the release is much closer, there is not enough time anymore to show every character in the rythm they did until now. I imagine we get a bunch of veterans(around 3-4) and more than 1 newcomer. Why? Well, a Direct is an opportunity for a character reveal, recently it was meant to be the opportunity for newcomer reveals. As time is running by and there may be more newcomer to show than it would be possible in the 2 month rythm. What if Nintendo were trying to release either the 3DS or the WiiU version already in summer 2014. There would only be the time for 2 more newcomers or maybe 4(if we were to expect 3 newcomers at E3). Until now we have seen already 5 newcomer(Villager, Mega Man, Wii Fit trainer, Rosalina, Little Mac) and I wouldn't expect less than 10 newcomers at last. So maybe we get 2 newcomers this time, 3 for E3 and maybe another one shortly before the release.
Also: How many veterans from Brawl are still missing?
Let's see:
SSB64 veterans:
Yoshi, Ness, Jigglypuff, Captain Falcon
Melee veterans:
Ice Climbers, Sheik, Mr.Game&Watch, Ganondorf, Falco, (Mewtwo as a special Melee veteran case)
Brawl veterans:
R.O.B., Lucas, Wolf, Meta Knight, Wario, Zero Suit Samus, (Pokémon Trainer not considered safe for the moment), (Ike may return, may not return), (Snake as 3rd party is a special case too)
I would see the SSB64 and Melee veterans as almost safe(9 without Mewtwo, 10 with Mewtwo). The Brawl characters are more difficult to put into categories. There are still 9 Brawl characters missing in SSB4 and in my opinion there are around 6 of them I consider likely to return and 3 I consider more on the edge. We could discuss the point if Lucas or Wolf were that likely to return or to be cut, but this here is just my opinion.
We have 19 characters still missing. If Sakurai were to reveal 2 per month, this would mean we still need more than 9 months for all veterans to be confirmed. This however would in the same time mean the game would be released in December 2014, maybe late December, and (!) there were no newcomer left to be revealed(except if Sakurai were to make the newcomer reveals as an addition to the 2 characters per month).
If the release were to be earlier like in the summer this year, let's see again. There would be 5 months left for character reveals. So even 3 characters per month would mean many cuts or many hidden characters which were to be revealed after the release of the game. However this seems a bit... I don't know. I expect Sakurai to reveal the full roster before the release as we already know the whole Super Mario characters before the release which is a bit strange.
There are now two good opportunities for multiple character reveals: the Smash Direct(would be perfect if he were to show 8 veterans at once and 1-2 newcomers) and the E3(similar to the Smash Direct: 8 veterans + 3 newcomer). If this were the case, we would have only 3 veterans left and a summer release would in that case be possible.
Of course it is more some sort of a wish we get to see many veterans in the Smash Direct, but hey, it's still not impossible. Maybe less than 8 veterans, but still would be great.
I think we won't have to worry about at least one newcomer reveal in the Smash Direct. However given this special opportunity, I'll expect 2 and maybe will have to see that I was way too optimistic.
Anyways. The veterans we may see, are almost necessary characters who can't promote anything this year anymore. As most of you will notice, there aren't that many characters who could promote something in the near future. Only Yoshi and Wario seem to be excluded for this one and perhaps Meta Knight if Sakurai were to promote Kirby Triple Deluxe in the West too. Perhaps Sheik or Ganondorf could be revealed for Hyrule Warriors release. The other one could however be randomly revealed.
So my predictions for confirmed veterans:
Sheik, Zero Suit Samus, Captain Falcon, Ness, Falco, R.O.B., Ice Climbers and Mr.Game&Watch.
Next is the question which newcomer will we see.
Chrom, Palutena and Dixie are three characters I would keep in mind. However as this is a Smash Direct this time around, I could also see Sakurai reveal one of the very big newcomers such as King K.Rool or Ridley.
I'll predict the following two newcomers:
Chrom and King K.Rool
After all this is what I'm predicting. I'm sure this won't end up being an 100% true prediction but yet I feel like it's still to some extend possible.