I don't think it would be hard to imagine one being smarter than they are now. Being able to do computations easily, learning new languages quickly, having the ability to multitask better, etc. Basically being a better version of oneself is easy to think about. What I think would be difficult is to imagine oneself being genius level. Creating/finding laws of Physics/Science that can guide future generations. A lot of times the way they think is so much different than a common person's, and the way they see the world is much more than what we do.