What psychological effects could my 3 year old have due to the absence of both his parents for two years?

Separation anxiety. A 3 year old is old enough to have bonded to both parents, assuming both have been consistently in his/her life. But he/she does not yet have abstract reasoning or the cognitive ability to understand "why" the parents are gone. And ability to soothe self is not fully developed. All these areas could lead to difficulty later. Results depend a lot on who'll care for the child during this time.