First lets take a look at the DC Universe. Would Goku and the Z Warriors be apart of the Justice League or JSA? Would Superman and Goku be friends? How would Batman react to these characters would some of them be Lanterns? These are all very interesting questions but what do you think?
With DC having so many characters dead, King Kai would be a very busy guy probably so buys for his own good.
Would The Z warriors be looked down upon as like mutants are especially the Saiyan race? That could be an interest route to tackle but at the same time it it could take away from the essence of the characters. I could definitely see characters like Red Skull, Loki and Thanos getting their hands on the Dragonballs and just going crazy with them.
I have to be honest I really want Wolverine to go head to head with Vegeta XD!!!