I mentioned I had more thoughts on fighters, here we go!
First of all I think that we all need to remember that there are a huge variety of types of battles that you can run into or try to foster, and as such there are a large variety of ships/fleets to design. Because of that any particular ship doesn't have to excel in every task, but it could still be a perfectly valid choice for other tasks.
Newtonian Aurora is going to have a larger spectrum of battles than Aurora, simply because the velocity spreads will affect each battle so much. At the low tech Steve has shown us you could have two fleets closing on each other at a combined speed of anything from 30 km/s to 30000 km/s. At the slower speeds lasers will rule the day, as they will have a longer range and do damage regardless of the velocity. Kinetic Missiles will also be effective, as they themselves will be able to accelerate to decent speeds at longer range. The faster you go the more slugs will start to be important. They'll never be as accurate as a laser, by eventually you'll get to the point where one hit will be crippling, if not fatal, and it will become worthwhile to put up huge amounts of flak for that purpose. Kinetic missiles will grow more important as well, as their damage also reaches collosal levels, with an improved chance to hit compared to slugs (with the downside of being able to be intercepted). Nuclear missiles will probably be similarly effective for a wide range of closing speeds.
And this is just a first run analysis, who knows what sort of arms races will start to pick up, maybe it turns out lasers stay effective at high closing speeds, because they end up being good at shooting down kinetic missiles, maybe at slower speeds you use nuclear missiles offensively, as nothing else gives the knockout punch you really want, but in a battle with shrapnel flying past at .1c they are used purely defensively in the hope of knocking out opposing kinetic missile salvos.
In the higher speed fights fighters will have an advantage because their small size will make it harder for them to be shot by the one hit required for a kill, while at the same time their kinetic weapons will be able to cripple an opponent orders of magnitude larger than them. In slower speed fights a fighter may actually have the delta-V to make several runs on the enemy, and the time to do it as they slowly close.
Also, each fleet you make may have to handle any of these combat situations, maybe you design a fleet purely to raid an enemy colony, blowing past at 20k km/s and not slowing down until the next system, but if you run into a defensive fleet that matches your speed to intercept you in the system before your objective at a tenth the speed you planned you could be in enormous trouble. I am guessing that flexibility and combined forces doctrine are going to be much more important in NA.
At this point in Aurora, a missile is just not able to give you the flexibility that a fighter can. That won't necessarily remain the case in NA, maybe in NA you'll be able to give a drone a waypoint, have him shoot off a few missiles, give it another waypoint, have it shoot off some more missiles, etc etc. I think many of us, however, are not anticipating that to be the case, let alone doing things like installing railguns on drones. However if we get to the point that Drones fly like a fighter, shoot like a fighter, and quack like a fighter, sure, we may not need Fighters.
I think part of the problem here though is that we are trying to plan battle fleets with one of the biggest pieces missing: sensors. With those mechanics up in the air it's really impossible to make an attempt to do the sort of analysis this topic entails. It seems clear that a lot of the lines exist between the beam and missile weapons now are being eliminated. Slugs and laser beams will be propagated, some missiles will purely be kinetic kill weapons, laser warheads are getting an overhaul, new shrapnel weapons will be introduced. I'm sure along with these changes huge sensor changes will come in. For example random hit chances are going away, which pretty much throws out the entire Beam Fire Control play book. There has been talk of locking on to targets with thermal readings, the increased combat range may require resolution tweaks, the list goes on.
Until we know how far out a capital ship will see a fighter and attack it, or how far out a fighter has to get before it can target enemies the main fleet can't, we won't know how much they will get you. Likewise, until we start to have a good idea of how hard it is to see and shoot down kinetic missiles we won't know if you'll have a choice to use anything but fighters. The battleship is obsolete in modern days because a fighter that costs a hundredth as much as a battleship can easily sink it. As we put more and more realistic physics into NA I'm a lot more worried about the battleship becoming obsolete than the fighter. People keep saying "why launch a fighter when you can launch a missile" the fighter is just as much a replacement to that Missile Cruiser as it is the missile it launches, because once the enemy's one-hit kill weapons arrive at your fleet, you're going to want them one-hit-killing smaller, cheaper warships.