A common V-8 architecture would be a simple solution if it were not for the times we live in. I'm sure everyone is aware of all the fuzzy science and politics that are dictating Ford's decisions. Some projects have to be planned 5 and 10 years out. Right now 2015 is real fuzzy.
Back to the future for a moment. There was a fiefdom battle that happened in the early 90's. New Windsor prototypes were built, heads, induction, blocks etc. They ranged from 5.0-7.0 liters. There was also a revised 8.3 385 engine complete with GT-40 intake, roller cam etc. A real ball buster! The Modular Mafia won this battle but lost the war so to speak. In doing so we lost a common architecture in the Windsor. Would these engines be economical today? NO.
Where Polling, Trotman, and Nasser dropped the ball was an all new clean sheet OHC common architecture that could have been built in 5.0-7.0 liter displacements. Some tried and all they could get approved was the Hurricane.
We have a Coyote and a Hurricane for now. Lets enjoy what we have. Hell the future may bring Hydrogen and CNG with a whole set of new requirements.