Could Gandalf die (again)?

[paavo]

most of the answers have said that gandalf could be killed like any other man. but in Fangorn, after Gimli's attempt to chop of Gandalf's head (mistaking him for Saruman), Gandalf says

Get up, my good Gimli! No blame to you, and no harm to me. Indeed, my friends, none of you have any weapon that could hurt me.

Doesn't that mean that he could not be killed? Of course Gandalf could have meant that his "spirit" could not be harmed but if Gimli would have succeeded to chop his head of, the surviving of Gandalf's spirit wouldn't really had helped Middle-earth and some harm would have been done. So I would say that Gandalf could not be killed.