At the end of the 90s the American Company Quiet Skies Inc. bought a former Air China B707 and modified it with Winglets and reworked engines.
So far I´ve not heard about any 707-operator giving its workhorse a new lease of life through such an modification. Are all 707 bound to die in a very short time then?
Without such extensive reworking the 707 will be gone soon because of environmental restrictions. 5 years ago you could see the occasional old 4-holer here in Europe, but now? Gone, except the Air Force machines.
Sad to see them go.