It all rests on the Ashes series across the Tasman. Before the current series the Black Caps (97 rating) were sandwiched between England (105) and Australia (97) on the rankings.
A 2-0 series win will boost New Zealand to 100 ratings points, however if England manage to win at least one test in Australia it should be enough to stay ahead of the Black Caps while Steve Smith's men would jump to third.
India are well ahead in the test rankings and look likely to extend their spot over second-placed South Africa with a possible 2-0 series win over Sri Lanka on the cards.