There are many artists who collaborate with other artists on certain songs. They do this because two great artists is better than one. Sometimes, new artists will collaborate with popular artists in order to grow as a musician. They also want to be more popular which they might because so many fans would listen to the music. Even though she is not new, I would like to see Katy Perry collaborate with Bruno Mars.
I think their voices would sound great together on an album. At this point, they have not collaborated but there may be some talk about it. It sometimes takes time to get a collaboration between two very well-known artists due to their schedules and due to whether it is a good idea or not.