FlatFuture.scala

import scala.util.control.NoStackTrace

package object FlatFuture {

  case object EmptyOption extends RuntimeException("Current option is empty :'(") with NoStackTrace

  implicit final class futureOfOptionToFuture[A](future: Future[Option[A]]) {
    def flatten(implicit ec: ExecutionContext): Future[A] = {
      future.flatMap {
        case Some(something) => Future.successful(something)
        case None => Future.failed(EmptyOption)
      }
    }
    def flattenM(none: => Future[A])(implicit ec: ExecutionContext): Future[A] = {
      future.flatMap {
        case Some(something) => Future.successful(something)
        case None => none
      }
    }
    def flatten(none: => A)(implicit ec: ExecutionContext): Future[A] = {
      future.flatMap {
        case Some(something) => Future.successful(something)
        case None => Future.successful(none)
      }
    }
    def flattenM[O](some: A => Future[O], none: => Future[O])(implicit ec: ExecutionContext): Future[O] = {
      future.flatMap {
        case Some(something) => some(something)
        case None => none
      }
    }
    def flatten[O](some: A => O, none: => O)(implicit ec: ExecutionContext): Future[O] = {
      future.flatMap {
        case Some(something) => Future.successful(some(something))
        case None => Future.successful(none)
      }
    }
  }
}

test.scala

import foo.bar.FlatFuture._

val fuuu1: Future[Option[String]] = Future.successful(Some("Hello"))
val fuuu2: Future[Option[String]] = Future.successful(None)
implicit val ec = ExecutionContext.Implicits.global

fuuu1.flatten.filter(_ == "Hello").onComplete {
  case Success(str) if str == "Hello" => println("It works")
  case _ => println("Error ...")
}

fuuu2.flatten.onComplete {
  case Failure(e) => println("It works")
  case _ => println("Error ...")
}