Is colorblindness as common a symptom of old age as the loss of vision?

No. Usually colorblindness is inherited or happens after some event affecting the optic nerve, but as one gets older, a cataract can decrease color vision.
Maybe. As cataracts develop, it may become more difficult to distinguish bright or blue colors. After surgery however, the color balance should be restored fully (much to the amazement of patients). True color loss may be related to optic nerve disease or may be genetically inherited. Also, with macular degeneration color perception may be altered.