Pakistan, the 1992 champions, need to win the series 3-0 to rise one place from ninth while their opponents -- champions in the first two World Cups in 1975 and 1979 -- need to avoid a clean sweep to maintain their current eighth spot.
Hosts England and the seven highest-ranked sides in the one-day rankings on September 30 next year will qualify directly for the World Cup.
The bottom four teams in the standings will be joined by six Associate sides in a 10-team qualifying round in 2018 from where two teams will qualify.
Both Pakistan and the West Indies will also play in three one-day matches in the Caribbean next March.
Pakistan also have a tough five-match series in Australia early next year but West Indies will be hard pressed to play England and India before the cut-off date.
Both Pakistan and the West Indies have varied problems in the 50-over game.
Pakistan, ranked number one in Test cricket, have slumped in one-day and are coming on the back of a 4-1 bashing in England, a defeat which almost cost Azhar Ali the captaincy, but he finally survived.