I think this is a good start for many people.
I definitely think this is the way to go as far as helping give the fighter more options and versatility in their abilities without coming up with anything too different or crazy. Make them like Invocations/Infusions where you get a certain amount to choose from at different levels, with more fantastical and epic options unlockable at higher levels. You could even throw in a few more non combat options in the mix so the fighter can branch out into the other two pillars a bit easier.
This could also allow for more mundane and grounded maneuvers to exist along side more mythical and supernatural maneuvers and allow for the choice.
I think a lot.
sounds like a great start.
give OPTIONS to take some supernatual uses of the SDice and ones that are higher level (more like 3rd+ level spells)
heck just counter spell... expend a Sup Die and roll X vs Y to use your sword or shield to bat a spell effect away.
One of the biggest regrets I think I have from the next playtest was moving superiority dice to a single subclass. I get they wanted the "roll to hit" champion fighter to be the training wheels class, but I think modern audiences can handle a fighter that got dice and maneuvers as core.
My idea would be to keep the core pool of maneuvers fairly mundane and leave the gonzo stuff to subclasses, but I'd still allow some heroic options in there as well (add superiority dice to the number of feet jumped vs jump's auto 60 ft). I'd also greatly expand the pool of dice to allow for more uses.
For subs:
Champion: bone simple abilities that add to either damage dealing or survivability. Reroll dice, added crit, that kinda stuff.
Battlemaster: gains more support stuff that makes you break out the battle mat and minis. A controller in 4e parlance with the ability to share his superiority dice with allies.
Cavalier: defender type warrior with lots of social abilities on the side.
Tracker: your non-magical ranger with bonuses to stealth, ambushes, and wilderness skills.
Arcane archer: use your superiority dice to fire Hawkeye arrows, fire, ice, seeking, putty, etc.
Psi-warrior: use your dice to basically do the psionic stuff they currently do.
Rune knight: mimic supernatural abilities like growing larger, powering weapons with elemental energy and teleporting around the room. A bit if the 4e sword mage.
Eldritch knight: add a small pool of wizard spells to your maneuvers.
If samurai somehow makes it over, he becomes the master of using morale rules and making speedy attacks.