FDR was a pre-TV, pre-internet president (an experimental broadcast at a World's fair hardly counts). Being in a wheelchair shouldn't affect the viability of his candidacy, but it would. In the 30's and 40's he relied on non-visual media, and the good will or the press to no print photos of his chair. When that failed he had agents confiscate and destroy unflattering photographs. That just wouldn't be viable today.

Also, he threw innocent American citizens into concentration camps because of their ethnicity. When issues with the current migrant crisis come up, or various other racially-charged issues, he's probably gonna have some unsavory opinions that will alienate him from the left.

The right will already hate him for economic policies.