Are there any general hints you may need root canal or extraction? Teeth aren't cracked yet but turning yellowish grey and minor crack. Going on mon.

Don't try. Don't try to guess what treatment would be indicated or needed. You'll find out soon enough once your dentist takes some x-rays and clinically examines your tooth.
Visit The Dentist. There is a strong link between good oral health and a person’s overall well being. Visiting your dentist twice a year will help make your teeth healthy.
A few ideas. Root canal treatment usually for decay that is close or into nerve of tooth. Extraction for non-restorable tooth, or when cost of restoration is prohibitive.