I love "Phase IV," but as a true fan I have to acknowledge it has some faults that made it less than perfect. The script needed work and there is the hammy taste of seventies hippism that infects mostly the end.
Other than that it's a great film. Ants start becoming intelligent and working together. A scientists notices this and decides to put himself (and his assistant) in peril to test and communicate with this new life form. It becomes a back and forth game of one upmanship as each species probes the other's weaknesses. There are some incredible creepy yet fascinating images like ants with runes on their heads or a brave soldier dying as it drags a samplle of poison to the queen so she can make immune soldiers.
What I would do here is clarify why this is all happening. Not only the intelligence, but the new venom the ants seem to have which is far more deadly than normal ant stings. I would also widen the scope a bit and let the ants take out a small town and not just a ranch. Make it clear they are a serious threat. At the end of the original there were basically two choices given to mankind; resist and die or become part of the hive. I want to make it clear in the remake the terrible, terrible price it would be to lose one's humanity joining the hive.
Anyway that's just me...