Zimbabwe were on six points with two games to spare, but they failed to get those two points which would have ensured qualification. If Netherlands beat Scotland on Thursday, then all three teams - Zimbabwe, Scotland and Netherlands - will finish on six points.
With Netherlands' net run rate in the negative but already above Zimbabwe's, any win for them will only improve that further, thus ensuring that Zimbabwe cannot finish in the top two.
Thus, the focus now shifts to the Netherlands-Scotland game, and the result margins for those two teams to qualify. A win for Scotland will obviously take them through, but even if they lose, they could qualify if the margin of defeat is relatively small.
If Netherlands score 250, Scotland can afford to lose by up to 31 runs to stay ahead on run rate. A win by 32 or more runs for Netherlands will lift their NRR above Scotland's. If Scotland bat first and score 250, they will stay ahead on NRR if Netherlands chase it down in around 44.1 overs (depending on how they get their winning runs). If they chase it down any sooner, then Netherlands will trump Scotland's run rate and take the second qualification spot.