Here's Sage's email to their Sage 500 ERP customers. I think if I were a Sage 500 ERP customer I'd just be confused. After all the email lays out some hope that the product will be supported past 5 years (using wording that says ""at least 5 years"").
Will this be enough to nudge people to upgrade to ERP X3? Probably not but it's probably only step one in Sage's master Sage 500 ERP migration plan.
http://cdn.na.sage.com/sagemail/SageMail/Sage%20500%20ERP%20Customer_Communication_082912.html