Although I believe the trilogy films have been sliding downhill, I would expect GF4 to be much better than GF3 - assuming they do it in the GF2 style of mixed flashback/present.

I would hope they spend at least 2/3 of the time on the "missing years" of 20s/30s - as Puzo probably already wrote the screenplay for this part - Puzo said (DVD Bonus) he gave it to Paramount and DeNiro. I would find the 20/30s history with DeNiro and a Sonny character (not DeCaprio!!) more interesting than some new material revolving around Andy Garcia and perhaps sissy Anthony returning to the family after his sister is killed ala young Michael after the hit on Vito.

The only required actors are DeNiro and Andy Garcia.