Neville will do what Dumbledore won't - this explains it all

[samnanya]

No: HPFGUIDX 92394

Deb in NJ
Having heard the prophecy, Dumbledore knows that no-one but Harry 
is going to be able to kill Voldemort, so that trying to kill V while 
inside Harry isn't going to work.

Samnanya
I disagree - that is DUMBLEDORE's weakness - but there is someone else 
who can and will do what Dumbledore won't. 
I always thought it unusual that Neville was responsible for the 
tie-breaking vote in SS for bringing the house cup to Griffindor. 
Dumbledore saved Neville's seemingly minor act for last recognition, 
after the larger contributions of Hermione, Ron and Harry. Standing up 
to your friends is very difficult indeed - and Dumbledore recognizes 
this trait as of utmost importance. 
I would not be suprised at all if at the end of book 7 it is Neville 
who stands up to a seemingly defeated and Voldemort-occupied Harry and 
"defeats" Harry/Voldemort in the end (or sacrifices himself trying), 
thus restoring Harry to full and exclusive control of his body. 
Harry will be able to defeat the physical form of Voldemort but this 
time the Dark Lord will retreat to where he is safest - in Harry.

BTW - That could also be why part of the prophecy is repeated TWICE. 
This is also in common with Trelawney's prophecy in POA which was 
repeated TWICE and also "happened" twice due to the time turner - the 
net result that the prophecy was true in both instances with Wormtail 
escaped in both instances.