I admire your optimism!
But I am also reminded of HIGHLANDER 2, BASIC INSTINCT 2, BLUES BROTHERS 2000, etc.
sequels aren't always equals!
But, it could be interesting if they stick to the odd structure they established.....
the most interesting thing to me about the first film was that it is essentially just a SECOND act film without a first or a thrid act.
It begins AFTER the first act (the invasion) and ends right before the third act (fighting back/war against them).
So, it is possible that the new film is simply the First act that leads up to the previous film (the second act), and a possible thrid movie would be the the third act.