No, I do think he will have let go, but later, beyond the end of this story. The Maglor-casting-the-silmaril-into-the-sea is such a popular scene already, so I wanted to do something (slightly) different, and not focus on the moments immediately surrounding the casting. 

Of course, not-letting-it-go could be an interesting follow-on. After all, it doesn't seem like there were any witnesses to the event... (/end au tangent)