The LBP series is in every sense a precursor to Dreams. The levels and games created by the community from the latest installment LBP3 (first released on PS3 and then later the PS4) could give is a rough idea of the kinds of levels players might create in Dreams.
Will player made content from Dreams surpass player made content from LBP3?
It's amazing to see the variety of content that people have been able to make given the 2D constraints of the LittleBigPlanet level editor. I say 2D, although by the third installment I believe players had 16 layers available to play with. Along with a set of tools that had been fine-tuned over the previous two installments, players had fairly ample creative freedom in LBP. Dreams promises to give even more of course, which is what makes it so exciting.