In my view, the Quran doesn't need to get changed / rewritten. You'd need a new Prophet for that.
But the Sharia could use an update, by removing the punishments for "social crimes" and "critiques of the Prophet or faith"..
Insecure xenophobes need to punish others for insulting their faith. Confident faithful just shrug and move on.
Oppressors need to punish others for "social crimes" in the name of their Lord. Confident faithful leave the punishing of social crimes to Allah.
And while the Quran does not need to be updated, like others have said here before, it's the current and future generations of Imams that determine how Quran verses get interpreted to today's situation. If they'd focus less on domination of others through violence that's (according to them) permitted by Allah, then Islam would become a "respectable faith" in the eyes of followers of other Faiths.
It would also allow the followers of Islam to get go of that notion that (militarily futile) suicidal violence serves a purpose and/or gets them to Heaven.
Islamic extremists glorify their own futile deaths and the deaths they cause among their own people. They're completely stuck, banging their heads against a wall so hard that they remove themselves from the gene pool.
If you'll allow me a metaphor: This is what i think extremist-islamic military strategy and tactics resemble at the moment;
Seperation of state and religion should also be put on the Islamic agenda. At the moment they're joined at the hip in Islam by the radicals.
"There can be no good statecraft without having Islamic principles as it's base." says the Islamic extremist; I'd say the generally more peaceful nations that have seperated church and state have proven otherwise thoroughly.