Ike was my character of choice in Smash Bros. Brawl, and also my favorite Fire Emblem hero, so I'd be ecstatic if he was confirmed.
I personally doubt it though. The main reason he appeared in that game was that Radiant Dawn released shortly before Brawl, and he was fortunate enough to be the most recent Fire Emblem hero at the time. It was the same story with Roy, with Fuin no Tsurugi being the most recent FE before Melee. For that same reason, I'm betting on it being Chrom instead. He uses Aether in combat, and his character design is closer to Ike than Marth, so it's possible his play style will be similar to Ike. I'd honestly prefer that to Lucina, who would likely come across as a Marth clone. Though both would be even better...
Though maybe they'll throw us a curveball and have Prium appear XD.