Well, if Edward wants to create all his brothers as royal dukes he'll need to find the land to sustain them. There's probably some heiresses he can marry some of them to to mitigate this issue.
If Edward still marries Elizabeth Woodville the fact that he's surrounded by 5 of his own brothers might block the Woodvilles from dominating court as they did OTL.
Richard or Thomas, as the younger sons, might go into the church- it happened to Lionel Woodville and George Neville.
Then, it really depends on personality- if one of them has the disloyalty of Clarence and the competence of Richard he could cause trouble. I'm not sure to what end- claiming the throne themself, removing the Woodvilles.
Finally, there's every chance that some of them will die young in battle or be executed after being captured- it happened to Rutland, after all.