if I buy one with ICS, would I be able of updating it to JB?

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http://forum.xda-developers.com – So my question is pretty simple: if I buy a Galaxy Nexus from someone on eBay (a Galaxy Nexus that is not for sprint or verizon) and the phone comes with ICS: would I be able of updating it to the latest version of Jelly Bean, so the phone is just like the ones that the Play Store is selling right now? PLEASE LET ME KNOW! AND SORRY IF THE QUESTION WAS TOO STUPID, BUT I JUST WANT TO BE SURE THAT I'LL HAVE A STOCK-STABLE JELLY BEAN VERSION ON MY PHONE (HowTos)