Let's not beat about the bush, Uncle Bob knows how to hang on.  He's battled worse odds when fighting for liberation and come though with flying colours so he's experienced.
Even before the Zim elections, I'd predicted Bob would still be in charge despite the outcome.  Why?  Because he has the desire to do so and after 28 years, the establishment practically works for him.

In the meantime, Mbeki is caught in a position that he's having trouble resolving since he lacks leadership.  Bob & Thabo were good friends and allies during the struggle so how can he turn on his old friend now?  This leads me to ask...  Surely as his good old friend, he could have talked sense into Uncle Bob or if not told the rest of us exactly where we stand with Bob!
So, Mbeki is a lame duck, the SADC is a wet fish and the AU...  I'm pretty sure that if it came down to it, they're just a department of rubber stamps.
What's the way forward?  Well, if I knew that then I'd be Uncle Bob but I'm not so I don't have the solution to hand.  Nonetheless, the so called leaders should be able to sort this mess out, we've been in worse situations and managed to muddle through.
I feel for all those suffering and struggling in Zim, here's hoping it works out to your advantage!