If Martha Firestone Ford wants to increase her chances of seeing a Lions team that has plenty of playoff success, she should stay the course with Bob Quinn and Matt Patricia.
If someone is willing to pay much more than the Lions are valued by Forbes ( for example ), it wouldn't surprise me if the Ford Family sold the Lions.
If the Lions are sold at some point, the question immediately becomes how committed is the new owner to the Detroit market? A market that was once the 5th Largest in the USA. Now, it's somewhere in the mid teens.