In an interview to be broadcast Sunday on CBS, the 61-year-old Neeson also talks about aging out of action hero roles. The interview includes a trip to Ballymena, his hometown in Northern Ireland.
Neeson said he and Richardson had agreed if either one of them was in a vegetative state they did not want to be kept alive by artificial means.
Richardson, daughter of Vanessa Redgrave and director Tony Richardson, was 45 when she fell on a Canadian ski slope in March 2009, suffering a fatal injury to her head. Neeson in the interview talked about entering his wife's hospital room.
"I went in to her and I told her I loved her, said, 'Sweetie, you're not coming back from this, you've banged your head,'" he said.
But he said he still expects her to reappear.
"There's periods now in our New York residence when I hear the door opening, especially the first couple of years ... anytime I hear that door opening, I still think I'm going to hear her," he said.
Neeson said Richardson would be "very thrilled and pleased" to know her heart, liver and kidneys were donated.
"Non-Stop," a thriller starring Neeson as an air marshal dealing with an in-flight threat to a plane, opens next week. He told CBS it is the kind of role he may be leaving behind.
"I'm 61 years of age, man, you know? Going around, fighting these guys, yeah, I feel a wee bit embarrassed, you know? " he said.