After being diagnosed with cervical spondylosis can anyone still go on to lead productive lives?

Absolutely. Most patients can be treated and often nearly completely relieved of their symptoms with either non-operative or operative intervention. It should not lead to long term disability for most patients.
Yes. Having cervical spondylosis does not equate to having neck pain. This often a finding on x-rays, mris and ct scan while brewing investigated for another condition. For those with associated neck pain. Treatments are available allowing you to carry on a full quality of life.