Carcinization gets so much attention because of how unique a process it is. We don't fully understand why Crab is the idealized form for so many environments, just that evolution keeps producing it over and over again. Will we find crabs on other worlds? Unknown! It's possible but we don't know if it's a rule of arthropoda or a rule of evolution or exactly how likely the crab for him.
With sharks, however, the answer is well known. Sharks are shaped that way - similarly to how swordfish and dolphins are of very similar shape - by hydrodynamics. Basically if you want to go fast to eat other things underwater, there's a very limited number of viable shapes, and most of those shapes are occupied by sharks.
If we go to another world, and we find life in alien seas, there's a good chance some of it will be shark shaped, molded by the same forces that made sharks on Earth.
however this means that there likely will not be space whales! they do not need to be aerodynamic