I totally believe that Itachi plans to use genjutsu to stop Edo Tensei.I think that Itachi is the perfect guy to stop Edo Tensei but it is true about the problem on how reaching Kabuto and the fact of the 6th coffin.
Genjutsu is also the only way to stop all the summoned at once.
Maybe we have Itachi vs 6th coffin soon.
Go Itachi!!!