I think, Blomkamp had a potential. I like his direction and films. And Alien 5 looked promising. Technically he could be a second Carpenter as a legendary storyteller.
BUT!
Blomkamp made a mistake. He started and stuck (and finished the career) with his African trilogy about poverty, inequality, class struggle and blah-blah-blah. Not surprisingly, people began to think that he couldn't film anything else. And his works were less and less successful. Again, because people don't want watch third times one film about blah-blah-blah.
And guess what? After Chappie (tbh better than D9 for me) his first indie film was again about beggars in rags vs alien invasion. I'm more than sure - Alien 5 also was about these themes.
I vote for Blomkamp only for a true Aliens sequel. But I don't care who will do it in the end: Blomkamp, Walter Hill or someone else.