Nope.
All the character reveals have been returning characters so far apart from the 3 newcomers they showed at E3. So if it continues along this path we should see him before anymore newcomers.
Even so, I doubt he'd be excluded, especially when you consider that Ness was a playable character since Smash Bros. 64.
Also there are a lot more people who are aware of 'Ness' and the 'Earthbound' series today than ever before thanks to all the recent hype from Nintendo Direct, Miiverse and the Eatherbound release on the Wii U eShop.