"Two can keep a secret if one of them is dead." It's implausible that so many people know Red John's identity, and yet it remains the best kept secret of all time. At this point, there would at least be rumors, whispers of Red John's identity.
Every week Jane catches the culprit with almost nothing to go on. Jane has hundreds of pages RJ files. Jane knows the specific locations and times of the RJ murders. Jane has a finite list of suspects. Come on, there is NO way Jane should still be this clueless. Process of elimination and old fashion police work should get the list down to about 10. I'm sure most of them have solid alibis for at least one of the RJ murders. Then Jane can have the rest under surveillance, play mind games with them, etc.
Oscar Ardiles...sure....why not?