Originally Posted by cavalierlwt
It's probably tough to try to keep coming up with small victories that are satisfying but would not lead to a rapid victory over the aliens. Remember when they wrote themselves into a corner with the super Mech bullets? They've got to win at times but avoid something like that.
The problem isn't coming up with something that gives the humans an edge - it's coming up with the right way to counteract it so they can't outright win and end the series. The simplest solution to the mech bullet issue would be to limit the number they can make. If they simply don't take down enough in a situation where they can collect the metal, they simply won't always have them.
Adaptive shields would be another way, but then you run into the problem of the humans needing to find ways to take down a mech that they haven't already adapted to or risk violating continuity.
Probably the biggest issue they've written themselves into a corner on is Tom himself. He's been captured so often, it make me wonder a) why anyone trusts he hasn't been compromised and b) why the aliens simply don't kill him and be done with it. The answer to "b" is that the show would be over, but it creates a discontinuity when he slips from their grasp in the process of handing the aliens a massive defeat, again and again. Further, he seems to be one of the few people able to rally the masses together to continue the fight, so killing him would likely kill the movement.
As a result, the simple solution is for him not to get captured. He's always on the outside trying to get those that are captured out. He needs to be a little less Kirk and a little more Picard and not be on every away mission. That's not to say he can't be put in peril now and then, it just feels like the aliens aren't even trying to defeat him and his army.
Of course, now we have Lexy who is a grown woman that has alien superpowers and becoming increasingly evil. She's also the child of two of the series heroes. That means, they only possible way to write themselves out of this is to have her have a change of heart at some point and sacrifice herself to save the humans in order to avoid the need for her parents to put her down. She can't just destroy the aliens and continue to live among the humans.
Honestly, I'm not sure where they go for the final season other than the typical everyone gets captured and escapes and we see yet another offshoot of the aliens we never knew existed in previous seasons.