Asymmetrical cheekbone structure and mid face descent, can anything be done to even the appearance? (photos)

Facial asymmetry is common to everyone. One side of the face is slightly less developed than the other side. When there are focal areas of asymmetry paired with volume loss, the differences are magnified.Facial contours can be improved with fillers, fat, or implants. I recommend consulting with a surgeon so she/he may examine you and take photographs. I like to use 3D computer simulation software to get on the same page as my patient regarding their aesthetic goals. The surgeon can then outline a treatment plan appropriate for your face for a safe and happy outcome. Safety comes first.

 Hi, I have performed many facial shaping procedures using dermal fillers, facial implants (cheek, chin), liposuction and/or facelifts for over 30 years. Following the beauty principles outlined in my book on face and body beauty, men look chiseled and handsome with angularity in the cheeks, chin and mandibular angles.  From the photos, your cheeks are flat anteriorly (in the front), the chin is weak as are the mandibular angles and there is evidence of "malar bags" on both cheeks.  These combine to create an elongated rectangularly shaped face.  The following procedures would create a more ruggedly handsome face.

Cheek augmentation with cheek implants to add angularity to the cheeks and mid face. 
Chin augmentation, using a chin implant, to add projection to the chin creating harmony and balance to the lower face.  I have performed many Chin Augmentations using chin implants for over 30 years.  From the photos, your chin is weak.  A weak chin creates an imbalance making the nose appear larger, the mid face top heavy and the lower face look short that de-emphasizes the lips and allows early formation of a double chin.  Chin augmentation using a chin implant will add projection to the chin creating harmony and balance to the lower face.   I have found that placement of a silastic chin implant, through a small curved incision under the chin (also allows excess skin removal) to be very safe, quick, highly effective and far less invasive than a sliding genioplasty.  I perform chin implant surgery in 30 minutes or less, often using a local anesthetic alone.  In my opinion, you are a good candidate for chin implant surgery.
Augmentation of the mandibular angles using a dermal filler (jaw implants have too many unwanted side effects IMHO) to add volume, angularity and flare to the jaw line.
Hope this helps.