Keeper league advice needed?

We haven't been forced to cut down to our 4 keeper players yet, so my current roster is:

QBs  Brees & Luck
RBs  Foster, D Murray, Leshoure
WRs  Wallace, D Alexander, M Williams (TB), Britt.  

I have considered the option of trading Brees for a high pick and keeping Luck.  I fear letting Luck go and regretting it for the next 12-15 yrs.  

options:
Brees, Luck, Foster & Murray
Luck, Foster, Muray & Wallace (Plus a high pick back for Brees)
Brees, Foster, Murray & Wallace
OTHER?