This doesn't matter much, buit some mid game predictions.
There are 4 characters I expect to be in.
Palutena
Dixie
Ridley
Shulk
As far as the first three, they are very important characters in their respective series and they have appeared in the most recent games of the series where they all had a major role. Shulk on the other hand, is from a new series. There aren't many other series with the same caliber. Though the series is small, it's not due to disinterest. Copies can go upward of 90 dollar or more. This suggest people really liked the game. It's a bit of a cult classic like Earthbound. In Japan, fans ranked it their 6th favorite Nintendo game (from Famitsu I believe). Plus, it has memorable music, locations (with Bionis and Mechonis) and the sword, the Monado. Beyond this, there some other possible characters. Chrom would make sense as well since Awakening did very well compared to other games in the series. The issue is there are 3 other Fire Emblem characters and it would be hard to fit him in. Rhythm Heaven could also get a character. King K Rool is a possibility, though he hasn't been in games for quite some time (as apposed to Dixie). So out of all the rest, these 4 stand the best chances in my opinion.
As for other stuff, it seems like we are going to get two characters a month. That seems to be the pattern at least. We may have 9 more months of characters which is about 18 more. This would be 42 characters. This number will likely be higher as more characters will be announced during E3 and closer to the game's release. Also, it seems like we'll have a Direct every two months. So I expect we'll see
April-Palutena
June-Ridley(E3)
October-Shulk (last newcomer before launch)
There will be more scattered in. The total number of characters will be between 45 and 48. I don't think Snake will return though Mewtwo will. Based on the state of Pokemon, there wont be a new character. Mii and Pac-Man likely wont happen. I don't think there will be anymore Third Party characters.