Odds were not great? At one point it was around @28ish, you sure your bet is on Zimbabwe or not Pakistan? Anyway it would be big upset if Zimbabwe went to win or draw the game against the Pakistan. Their bowlers should roll them over quite easily imo.
Given the unpredictability of Pakistan, it looks attractive to make a bet on Zimbabwe. But the problem is with the format. The chance of an upset occurring is very low in test matches, when compared to the shorter formats. For the last 10-15 years, Zimbabwe hasn't produced enough quality talent, to make up for the loss of their white players who have emigrated to countries such as England and Australia. Zimbabwe is just like a patient on ventilator, who is being kept alive in the form of annual funds form the ICC. When the funds from ICC cease to arrive, the cricket in Zimbabwe will die out.
I think the cricket in Zimbabwe already died out. In the last 10 years, you will only see Zimbabwe performance going worse with no hope of any change. With no funds, its hard to imagine any emerging cricketing nation to perform well. They need to rebuilt their domestic structure which look impossible for now.