What I see is mechanically very similar to paladins and fluff wise effectively an eldritch knight. Also a lot about what they are not (no oaths, no wilderness, no books) and very little about what they are.
Every class is at least partially defined by what they aren't. Druids are like Clerics without holy spells, being replaced with nature spells, that can't wear metal armor/shields, and can turn into animals. A Warrior Mage class would be like Paladins without holy spells, instead with arcane magic (wizard-style magic), protection features instead of healing, and capable of using their main weapon as a spellcasting focus. That's the same level of differentiation between a Paladin and Warrior Mage and the Cleric and Druid.
A part of a class's identity in 5e is always what they can't do. Rogues usually can't attack more than once a turn and make up for it in Sneak Attack, paladins can't use ranged weapons with most of their class features, Wizards can't heal like Clerics/Druids/Bards can, Barbarians can't cast spells while raging, Monks can't wear armor or use most weapons, et cetera. What a class cannot do is just as big a part of their identity as what they can do.
I'd also like to point out that in 5e arcane/divine divide exist in one fluff box about Forgotten Realms, so I don't think 'arcane paladin' is enough, just like 'divine bard' wouldn't.
I didn't list that as the only identifier of them. Arcane is a part of their identity, just like it is for the Wizards, but it's not the only one.
Now if in a reboot eldritch knight subclass wouldn't exist, then at least that overlap would be avoided, and perhaps eldritch knight could be its own class. But it still seems super thin to me.
If it were up to me, there would be no Eldritch Knight in the next edition/update of D&D, at least not as a Fighter subclass. Probably no Bladesinger or Arcane Trickster, either. Yes, there is overlap there, and it would make things confusing.
I just don't find this compelling.

Mind you, this is very much a preference thing. If enough people finds it compelling, then it could be a class. But then again, I'm not only one here asking these questions nor has WotC added such a class even though they've had plenty of time, so I don't think I'm alone in this.
I think the main reason why they haven't added such a class is because they're generally hesitant to add new classes in the first place and they need a good reason to add it. The only new class since the PHB came out 5 years after 5e had started, and that's only because having an Artificer is core to the idea of Eberron. They tried to have it as just a subclass of the Wizard at first, but when that didn't work out, they eventually took a few shots at making it its own class, and eventually succeeded.
If they end up making a product that really needs to have a Swordmage-style class in it (which I don't think there is one yet, but they could make a setting that requires it), that's when they would add it. Not just in a Xanathar's/Tasha's book.
Now, do I think this is likely to happen? Not at all. I do not think that a Swordmage class will ever come to D&D 5e, as much as I want it and believe that there is a place for one. It's just not necessary for any settings or worlds in the way that an Artificer is for Eberron or a Psion is for Dark Sun. But it could happen, and I firmly believe that they could make one that would be different enough from existing classes/subclasses that it could function as its own class.
Personally I would like the class to be defined less by what it is not and by it's relationship with other classes. I want it be something else than just a wizard/fighter multiclass with smoother mechanics. I don't think 'combines fighting with magic' alone is enough, it needs to come with metaphysics and a narrative. I find things like Death Knights and Witchers compelling. They're their own things, not just hybrids of other things and come with an interesting story.
I personally like classes that can tell a lot of different stories and themes in them. The Rogue has everything from a swashbuckling pirate, to a stealthy assassin, to a burglar, to master tricksters that use illusions and enchantments to scam others, and even to a murderer that steals the souls of his victims and uses them to become incorporeal. Barbarians have shamanistic-Totem Warriors, Nordish Berserkers, warriors that draw power from the spirits of their ancestors, lycanthropic beastmen, and spiky-armored juggernauts. Rangers have people that wander the Feywild, underground ambushers that become one with the shadows, protectors of this plane of existence, and monster hunters. Warlocks have people that have sold their soul to the Devil, insane cultists to Elder Gods beyond the stars, heralds of watery beings from oceanic abysses, people that serve Genies and become like them, and edgy warriors that are bonded to cursed swords from the Shadowfell. I could go on.
I'm fine with having a base class that's fairly bland theme-wise, but subclasses that are extremely focused on different themes. In my opinion, every class should be like this. The base class is mainly there for the mechanics and basics of what sets you apart from the other classes, with the subclasses doing the heavy-lifting in the story department. Class is generic ("Fighter", "Rogue", "Barbarian", "Cleric", "Ranger"), but subclass is specific ("Rune Knight", "Arcane Tricksters", "Path of the Beast", "Twilight Domain", "Fey Wanderers").