In terms of character reveals in this upcoming direct, I still find myself leaning towards (and wanting) a Shulk, Mewtwo or K.Rool reveal, along with at least one returning veteran (as I am not placing Mewtwo under that category). If I may be very hopeful, though I find it to be unlikely, perhaps we'll get an additional veteran confirmation on the Monday prior (or anything that isn't complete throw-away would suffice).
I would like to point out that Shulk, while not of course certain, does have a small thing or two going for him to be revealed Monday or Tuesday (so Tuesday, ha ha). For one, SorayaSaga has just tweeted about the Smash Bros. direct coming up. For those not in the know, her tweets usually hint around upcoming information regarding to her / Monolith Soft's related games. As I've also recently stated in the Shulk character support thread, Xenoblade Chronicles' 2 year (North American) anniversary is April 6th, which would be this Sunday (or tomorrow). Now I understand that anniversaries aren't always relevant, one outside of Japan at that, but it is still something to take note of. That, along with things such as Sakurai's picture of the Monado, Xenoblade's critical (worldwide) acclaim, and his character popularity being fairly prominent both East and West, we could be gearing up to see Shulk in action very soon (and as my personal most anticipated newcomer (along with K.Rool, Mewtwo, and anything related to new character material for the Zelda franchise) , I for one would find myself very pleased with that).
The things that I personally would be interested in seeing and hearing from the direct range from subtle to more "significance":
- Menu / Character select screens and navigation
- At least one newcomer and one veteran reveal
- A couple of new stages (A Xenoblade Chronicles and new Final Desination stage reveal come to mind)
- Perhaps a full match of gameplay, along with further video of new stages we don't quite comprehend fully
- Online features (MiiVerse, recording gameplay and anything akin to leader boards, lobbies and voice chat would be incredible)
- A further look or explanation into new gameplay mechanics (the modified edge guarding, etc.)