Why not resurrect him as a (semi-regular) Other? That would add the requisite-for-him drama for Dom, and sure add an interesting dimension to the whole Lost series. Also, I'm still not sure what happened to Charlie during that half-insane episode where he baptises Aaron. It was not apparently heroin-withdrawal. As far as I'm concerned, it's never been adequately explained - but you could do it if it was Charlie becoming somehow "otherly" through his experiences on the island, which would make a resurrection possible, and a resurrection as an Other amazing! I think Locke is now virtually unkillable, and by extension, Charlie could be too.