I don't think it's fear of flopping (although having those #1's means something to him)
But I think Hov knows he can't make the impact he used to unless he makes those grandiose guest appearances (he's like Andre 3000 now when you think about it). Over a whole record, where does he go? And maybe the route is to just have one producer, not a long record, just enough time to tell us how much better he is than us. Nas has Hit-Boy. Maybe Hov links back up with No I.D. again. I don't know if there's another producer that fits Hov sonically now over an entire project (like I don't wanna hear Hov spit over 12 Harry Fraud or Alchemist or God help us all, Timbaland beats)
I would welcome a Jay album from any of those producers for different reasons. I would love to hear what an Alchemist produced Jay song would sound because it would be something different for both of them. What I've heard if Harry Fraud is dope. Timbaland and Jay have obvious chemistry and a 12 track album would be interesting depending on where they go with it. They've done records that were huge in the clubs and the streets, but I would like to hear Jay get his emotional and even story telling bag over his production. "Jay Z Blue" was a glimpse of what could be.