Nixon was already prominent, due to the Hiss investigation. Bush had run a strong second to Reagan in the primary. None of these guys are as well-known as Nixon is and none are likely to run strong.
The one potential candidate Medved left out entirely was Gingrich.
I agree that none of these guys would make strong candidates for the number one spot, but they ALL are probably more accomplished than Dan Quayle (with a couple of exceptions). Politics, indeed, makes strange bedfellows. I don't think Newt wants to bother. He's making too much money on the outside looking in...and throwing an occasional bomb over the wall.
Gingrich is a weird case. If he got in and took it seriously, it would be a big 4. But he doesn't have money and can't run a protracted campaign. He claims to be hedging his bets, but if he doesn't get in now, he's done.
Medved said on his show yesterday the Newt has zero chance. I actually think he's right, just because of what the media will do to him. Bush's MSM coverage would be considered positive compared to what Gingrich would receive.