These super intelligent computers will hit a ceiling when people hit a limit to the amount of resources they are going to provide for some computer to solve the universe.
Or maybe the universe isn't that hard to solve and all we need is just beyond Einstein intelligence and then beyond that there is no more intelligence to be had once there is nothing new to learn.
I guess if they find a way to get an Einstein smart computer to the same size and the same power requites of Einstein himself, or perhaps even his brain only, more is possible than I can consider.
Humans have learned a lot by physical experimentation and observation, and these.computers won't be able to physically construct the experiments necessary to continue learning. Maybe they can come up with a design to try, but it's going to take humans to lay the bricks until we give them some way to physically interact with the environment.