I know by definition anything we come up with at this point will be considered fanfiction but thought it would be fun since I boasted I could come up with at least 10 different ideas. Here's mine off the top of my head.
1) We find out saiyans are actually a race of genetically modified apes by being from planet Truffle and were originally designed as protectors. Their ancestors were originally earth apes and were harvested prior to humans evolving. Because they share a common ancestor it explains why they can mate with humans. We also find their unique genetic manipulation allows them to mate with most kinds of humanoid races and in their journey through or to different universes they stumble upon different saiyan high-breeds with unique transformations and powers based on what
race they mated with. End boss is Saiyan Prime. The original genetically modified Saiyan kept in stasis for eons, and too powerful to use, but was originally harvested for his genes.
2)Instead of the God theme we could have them find out they are actually a magical race of beings which explained their ability to transform and change size and why they get so powerful so quickly. Opening up the realm of magic to Saiyans and their origins could have some fun concepts.
3)Z warriors could learn elemental powers and use these elements in combination with each other in concerted attacks. This could also go along with or against the magical origins.
4) In the present time line, it is found in the near future that the events allowed another race of warriors to rise up in frieza's absence and become more powerful/stronger. By the time they get to earth they are far stronger and outclass Saiyans in raw power, but if they go back in time they can fight the army before they become a threat. Bulma makes a time machine and the Z fighters , Vegeta, and Goku travel back and lead the uprising against Frieza and then train the other saiyans and turn their saiyan army of the encroaching threat.
5) Another fun form might be Cybernatic or Android Vegeta. In order to save his life from disasterous fight Bulma needs to use doctor Gero's technology. Vegeta could be a combination of training and Bulma's cybernetic advancements.
6) For some reason the Saiyans need to go to a planet of Giants. In order to compensate Vegeta begins training them to use and maintain their Oozuru forms. Gohan, Vegeta, Goku, and Piccolo are the only ones able to go on this adventure, but think of it as Attack on Titan X Dragonball.
7)Parody form - Goku gets stuck in his Oozuru form but is able to still function. Tries to take Goten to the park or help Chichi with dinner.
The series could focus on becoming more technique and weapon driven, things such as sword and techniques like creating multiple copies of themselves become common place or even a "fission" power.9) Not really changing the Saiyans form but some sort of space pirating adventure could be fun.
10) Parody- Saiyan sports. Basketball Goku, Vegeta baseball, etc.
That's all I got, I know these are pretty crappy but this is what I came up with off the top of my head. With no real thought put into them.
