I don't think length of time is the rational indicator of whether or not the status is still necessary, the present conditions within the country would be the rational indicator, yes?
For me personally, the conditions should be as safe or safer than the current conditions under which a person resides before considering removal of protective status, or else it would be cruel and inhumane to move them (to worse conditions).
I think preventing unnecessary human suffering should be the number one concern, do you not?