I was there last October.
If you are in the public part of the park, you need to have 300 or 400 mm at least (on a crop body) to capture
lions, rhino's and leopards.
If you are on a private lodge in kruger park, your 70-200 will do. These guys are driving you right next to the animals...
Had some lion cubs in about 15 metros distance and a leopard just 10 metros from the car !
Anyway, if you are into birds, better bring your big lenses (as usual....).
Regardless, what option you are going for, it is really worthwhile !