I don't think they could possibly get away with this NOT coming to trial.
They could, if they wanted to hang certain members of the police force out to dry. For example:
Any evidence in the custody of Hilton Botha, or evidence that had been under his jurisdiction declared inadmissible on the grounds of incorrect procedure (that's most of the physical evidence gone, plus any original statements made by OP and witnesses).
Further witness statements could then be called into question on the grounds of delays in obtaining them - how accurate would they be?
The court could then state that the case against OP, on the charge of premeditated murder cannot proceed as there is insufficient evidence remaining to prove anything beyond a reasonable doubt.
Given the incompetence of Botha at the bail hearing, I doubt it would surprise a lot of people if the courts were able to show compromised chain of custody wrt evidence as a result of his (in)actions.
Voila, a get out of jail (relatively) free card for the SA courts and OP.
(I'm not suggesting this would happen, just a possible route by which trial could be avoided).
The other option of course is that a guilty plea to culpable homicide is accepted...no need for a trial then either.