Oil futures go out to exactly the expiration date of the futures contract. Equity shares go out as far as you like. What makes the later years worth less is t

Oil futures go out to exactly the expiration date of the futures contract. Equity shares go out as far as you like. What makes the later years worth less is the discount you put on future cash - according to the time-value money principle. ie. future years are discounted proportionately dependent upon the expected inflation/discount rate. So yeah, 20 years is normal.