Not really.
You can’t imagine any mythic traits and capabilities tied to the attack action and individual attacks, thus leverage both the fighter’s many attack action attacks and multiplying the impact of action surge?
You don’t think the suggested replacement of indomitable with a version of legendary saves would contribute strongly to making them mythic?
Does breaking tangible spell effects require a different class? Does allowing special attacks with tactically useful secondaries?*
What about making the fighter able to do things like a special attack that lowers AC until the target does something to fix what they broke, plus all the special actions/attacks in the dmg but the fighter can do them as part of an attack, only losing ability modifier damage on the attack?
And the rogue is full of stuff that can be leveraged to make them more mythic in high level play.
- Uncanny dodge is an attack now, and if it hits, the damage is reduced by an amount equal to the damage you’d deal with a sneak attack with that weapon. Any damage leftover after reducing incoming damage to 0 is taken by the attacker (haven’t done any math on this)
- Make Uncanny Dodge no longer require a reaction
- Let them use Cunning Action any time they are missed or succeed on a Dex or strength saving throw
- Add new Cunning Action uses, depending on what skills look like in 2024
- Let them hide when in plain sight, or at least when only lightly obscured
- Have adv on attacks made with the same action with which you draw your weapon
- Mastery stuff with light and finesse weapons (this would be good at low level, even)
- Disarm spell effects like they’re traps
- Interrupt Spellcasting (could be a feature gated behind a subclass or a secondary choice of 3+ options) and if they roll well enough to do so steal the magic in a gem that can be used to cast a spell, charge a magic item, or boost a spell
- Give them some sort of limited resource like a Backstab or Lethal Strike that has stricter requirements than SA or can only be done x/day and juices up sneak attack
- Maybe fold some Thief stuff into the base class
- Acrobatics or Athletics check to do above Olympic level stunts
For fighters and barbarians especially, but all weapon users can benefit to a degree, give higher level benefits to Weapon Mastery.
Basically give types of weapons and weapon “sets” (like two weapons or sword and shield) short-description features that are similar to pbta Moves.
They would be different from eachother, and make it feel more like what specific weapons you’ve mastered matters.
Barbarian could expand Danger-sense somehow, and eventually gain resistence to magic. No way Bear Totem should be the only way to get generalized resistance to damage. They should also have benefits to intimidation.
At high level, Barbarians should be throwing plate armored horses at people, have a frightening aura while raging that also increases ally damage, absorb energy based damage types and either heal or extend rage or something cooler than that. (Headache, can’t think of cool features)
*special actions and attacks: