Well, that code exists at all for compatibility with tuples, which are a misfeature from the early days of scala. The "right" way to solve the problem is with shapeless' HLists. With HList you could write a simple generic method that would work with a HList of any length. (If you don't need to join a bunch of hetrogenously-typed futures while preserving all their type distinctions then you could just use the method that takes a Seq, above in the file)

(You could also generate exactly this code with macros, which were a new feature in scala 2.10; I imagine a newer version of the code will do that)