The Eisenhower - Obama analogy holds up even if we extend our analysis to young voters and minority groups--provided we focus on 1956 rather than 1952. In 1956 Ike was popular among voters under 30 and Black voters, as was, of course, Obama. In 1952 however, at the height of the Red Scare, most of the pro-Eisenhower (or perhaps anti-Stevenson) vote was older and white, like McCain's in 2008.
Eisenhower lost the black vote in 1956 by a substantial margin, he didn't even crack 40% despite winning the NPV by 57%. Also, do you have any data showing Eisenhower's relative popularity amongst young voters, or is this just an assumption based off "Youth for Eisenhower" or something of the sort?