It's not really about 'hitting targets' is it.The board aren't blind to the fact that major titles bring more commercial revenue etc. They're aren't blind to the fact that we haven't made a major impression in either the league or CL over last 3 seasons. They know Wenger is the common denominator, they know he's responsible.
They're giving Wenger the benifit of the doubt. Which is more than fair enough considering the consistency, CL money and participation he achieved during a difficult financial period for the club.
I don't the board will ever sack Wenger nor should they imo, it's a very unique situation in football. If we have a poor showing in the CL I think Wenger definitely walks at the end of season regardless of top 4 or FA cup. I think he'll examine the last 3 seasons where he's finally been backed with resources and self assess if he has the ability to take this club forward.