chasing points on the hard courts after the u.s. open for the express purpose of qualifying for WTF is a very bad idea.
it can lead to injury which ends the career instantly, let alone doing anything in 2016.
I would skip WTF and use the time to practice long and hard on the clay and to work on fitness.
he has to minimize the incidence of injury at this point because 2016 is all he has left.
I think he will leave the sport at the end of 2016 if he cant win at all and if he is out of the top 20 by then.