Endo thinks my tsh of 8 is due to a commercial soy diet. he wants to retest in a month to see if its returned to normal after discontinuing the diet. whats the chance it will recover? anyone have experience with this?

Only a tiny chance: While eating large amounts of soy may suppress thyroid function usually this is only those who are eating fairly high amounts of soy; see https://tinyurl.com/tt3zp6x for details. Besides rechecking TSH check Free T3 and Free T4 and thyroid antibodies. See https://tinyurl.com/yyp9bkon and https://www.verywell.com/practitioner-thoughts-thyroid-issues-3233024