I'm hoping to upgrade my iMac model later this year (Mid-2010 model, getting pretty old!) and as my current workspace is made up of a 27" iMac and Cinema Display, I would like a new 5K iMac to be able to support a 5K external monitor. Whilst we wait for Apple to eventually release their 5K Thunderbolt display, I could live with using the Cinema Display I already own as an external monitor with the 5K iMac. My concern however is if I were to purchase one of the current 5K iMac models, would it be able to support a 5K Thunderbolt display if and when it eventually releases? If not, I'll strongly consider holding back until a new set of iMacs emerge with that capability.