Honestly, does no sequel hurt, or help this movie?
deep down, to me, it kind of hurts it, its a good stand alone movie, love the action, the story....but without some kind of a resolve... personally i think it hurts the overall movie
the aliens just leave and meekus turns into an alien.... again, that alone is cool,...but i thought we were going to get a bit more...
personally i'd watch district 10/11/12/13 or whatever it will be called if there would be sequels, because i love district 9.
but seeing how MANY sequels of original movies only are made to cash in and sort of hurt the original (jurassic park for example?), it might be a good idea to just leave d9 as it is.
it is sort of an open ending. will the prawn (forgot his name) come back with an army to kick arse? will wikus be able to turn back into human and reunite with his wife? if a movie was made, we would not have to imagine the answers for these questions anymore.
If a sequel comes along, I imagine it'd be what Independence Day 2 should've been, but with Christopher Johnson on a rescue mission, leading a full-on assault on humans.
As District 9 starts with the human POV and slowly becomes more empathic, shifting to the prawn's fight for survival, it'd make sense for the sequel to be the other way around, starting by showing us a pacific alien race arriving to salvage their remaining citizens then getting delayed by humans trying to use their weapon technology or making it look like we're the ones instigating a war. Then, slowly focus on the humans again, as people actually start getting scared of losing the planet, and just leaving the aliens alone, coming full circle with the first one, while also commenting on us humans's entitlement to everything we know exist.
So, yeah. A good, thrilling sequel can emerge. It's not really necesary, but if comes to fruition, there's a lot that can be done in this universe.