Sliding genioplasty reversal. Will this cause sagging tissue and affect my breathing? (Photo)

I had 8mm sliding genioplasty 3 years ago. I’m badly suffering from persistent tightness and discomfort. I plan on having a 4mm sliding genioplasty reversal ( half way back ) to see if symptoms improve. I was told this will cause sagging tissue in the chin and neck and my breathing would be affected because the air way wouldn’t be as open and it would cause sleep apnea when I get older. Is this true?