Comparing MH370 to Earhart's plane is like comparing a muzzle loaded black powder canon to a GAU-8, two things that are technically in the same class but are on opposite ends of technological advancements. Earhart's plane was a prop plane that at worst would've been reduced to mangled scrap metal, MH370 on the otherhand was a passanger jet that at best would e been reduced to mangled scrap metal at worst it would've been effectively disintegrated with only the most durable elements holding up.

I doubt we will find anything more substantial than a flap or maybe a reinforced section of MH370, maybe a bag or suitcase on the smaller end. The only exception would be if it ran until put of fuel then glided until impact with the ocean or land, but even then it'd probably be pretty badly damaged and hard to identify.