Ralph is 64-66 yrs old, in that age range I think, whereas Karen is significantly younger at 50-51. In all practicality, Ralph can retire right now and be happy with what he's accomplished in the sport of softball. He's had a good ride. It's a Hall of Fame worthy resume. That elusive national championship or two he's missed out on wouldn't keep him up at night, I doubt.
Correct me if I'm wrong but I don't think there ever was co-head coaches who've won a national championship of any kind together. How clearly defined the responsibilities/roles might be between the two, having two head coaches/two potentially dissenting voices can sometimes cause some confusion/chaos at the players' end. And we need every opportunity and advantage to go our way to win a ball game. Who's the real CEO and who's a supporting COO? I think with a tandem of wife & husband we have it's helpful in recruiting. Kids can identify with them b/c they've dealt w/ their parents all their lives. It reminds them of their mom and dad. We always seem to get a top 5 recruiting class yr in and yr out to prove that point. But, once they get on campus and start going through daily work outs, team meetings, film sessions, batting practices, bull pen workouts, conference competition, post season play, et al, maybe we need to have one dominant person to take a full charge who can direct all the traffic with firmness and precision of a surgeon instead of a team of two who might disagree and argue on strategies, pitching sequences, starting line-ups and so on. It has worked for most part getting the program to the 7 WCWS appearances in the last 11 yrs. But a lot of great players have helped achieve that.
Of course, if they come back and reach that pinnacle --win it all next yr or the next two all these concerns go away immediately, buried for good and never resurfaces again...