How safe is Harry?

[David L.]

No: HPFGUIDX 135635

I think we are all assuming that magic draws its power only from the caster 
and once the spell terminates it means the caster has died or cut off his 
energy supply to the spell. Dumbledore said that Harry is protected once his 
bloodline resides in the Dursley house. This could mean that once Dumbledore 
started the spell he set the spell up so that the spell's contuinance is 
dependent on Harry's blood relatives surviving and not on Dumbledore himslef 
keeping the spell going. So unless something happens to Petunia and Dudley 
then Harry's safety is not in jeopardy. It could also mean that all three 
are protected; Petunia, Dudley and Harry otherwise Voldemort could have his 
DEs take them both out to get at Harry but that is complete speculation on 
my part. 

We all know that Hogwarts is a vast store of magical energies. This could be 
one of the reasons that its protective spells arwe there for so long.

David L.