We cannot predict the likelihood because there is so much diversity in tissue types. You may never be identified as a match for someone needing a transplant.
Or if yours is a common tissue type, you may be identified along with a number of other potential donors who match a patient. The patient’s doctor decides which donors will be contacted. If we call to say you are a match for a patient, you may turn out to be the only one who can save the patient’s life.