In seriousness, the only thing a fighter really needs is something to do outside of combat. Right now, He is dominant in the combat columns,
Not really, no. The Fighter has a clear role (tanky DPR) in combat, and the distinction of being 'best at fighting' (with weapons, without magic), which is a matter of differentiation, not dominance.
And, while the fighter is potent in the combat pillar, it is not particularly versatile, even within it.
It is tougher than the rogue, and doesn't hang it's DPR, on SA (with SA every round, the Rogues DPR is competative). And, 5e 'balances' that by making the Rogue superior to the fighter in the other two pillars.
That's not really necessary, most classes can be quite effective in all three pillars. The non-casting sub-classes of the fighter, rogue and barbarian are still designed as if they needed cross-pillar 'balancing' and niche-protection to keep them balanced along-side heavily limited casters, even though said limitations are long gone, and, to differentiate themselves, in concept, event though there are now backgrounds for that.
but could use some work in the exploration and/or social columns. I'm fairly certain that can be done without killing the rogue in the process
The fighter and rogue are different enough in combat, that they could remain differetiated, even were they some how rendered indistinguishable outside it. So, yeah, not a concern. The rogue, unlike the fighter, has gained steadily as the game evolved, and hasn't lost much beyond the flexibility/peak power of dailies in 5e, and no longer needs the niche protection that would demand it's strict superiority outside of combat.
A class in 5e doesn't lock up a concept the way it did in the early days, but some of the classes are still blinkered as if that were still meant to be the case.
If the fighter and rogue - and barbarian - were all brought up to par in each pillar, they might have very similar capabilities, but that wouldn't necessitate the demise of two of them, anymore than it had required 5e to do away with all but one or two caster classes.
It wouldn't
necessitate that demise, they could all stick around for 'in a past PH'/someone's-favorite-class purposes, but consolidating them would only make the game simpler and more playable, were it not for such backward-looking considerations.
My comments about the original thief being a mistake, and the combined abilities of fighter and rogue not being overpowering were a single class to have them were on the evolution of the game, not a definite plan to change it.
The bigger problem is Combat + Exploration is the dominion of the Ranger class, while Combat + Social is where Paladin hangs and where a hypothetical Knight/Warlord archetype lives.
What you're implying, there, is that the game only has room for three classes: a Combat + Exploration class, a Combat + Social class, and presumably, a Social + Exploration class.
Obviously, that is nonsense.