This is true. However, AppleInsider.com has a fair record of analyzing the facts and predicting new products (patent registrations, supplier comments and orders, when the product pipeline starts to dry up pending a new product, etc). They seem to think that new MacBook Pro models are due out, and the iMac line is WAY overdue for an upgrade based upon Apple's history of refining its hardware.Nobody knows anything... 'concrete'.. It's all speculation... really.
As the WWDC is only next month, I'm waiting to see what announcements get made. If I don't want to spring for the new model, then you'll surely see opportunity to get the older ones or refurbished models.