A lion is major predator in an African savanna food chain. What would happen is the lion was suddenly was removed from this food web

Considering the role that the lions have in the African savanna ecosystem, and the animals that they are hunting, their elimination from the ecosystem will for sure result in changes in it.

If the lions suddenly disappeared from the ecosystem, there will not be an increase in the animals they prey upon, as the food resources are limited for them, but there will be an increase in the numbers of the other predators.

Since the niche that the lions occupy will be free, their closest rivals, that are also able to take down larger pray, will increase in numbers, mainly the pack animals, like the hyenas and the African wild dogs. Both of these species will have open space for further going up the food chain as the strongest ones are no longer present, so the chances are that apart from the increase in numbers, there will be an increase in size as well in these two animals.