WOTC is denying it either way. We're no closer to a mythic martial than we are a caster overhaul.
But there is the argument that Casters as they are aren't what the game needs (nevermind more of), so if we were to assume we were getting such substantive changes to the system, then theres debate to be had over what to set as the baseline to revolve those substantive changes around.
I and others obviously think the Martials are, if not at the ideal baseline, at least closer to what it ought to be than Casters are.
Thats ultimately something I don't think many have touched on. Does everyone still posting here actually want busted demigod Casters?
Some I think may well be taking their existence as granted when thats probably not the ideal place to discuss this, despite what any practical observations of WOTCs own preferences might suggest.
I agree with you and want a full overhaul of magic. That said, it isn't at all equivalent. Full overhaul of magic and casters is a huge endeavor that won't happen until 6e if at all, whereas adding a seperate mythic martial class in an optional spatbook seems like a much easier lift.
I agree this is not an ideal solution. But at least you can have demigod martial hanging out with the demigod caster. High level might still be broken but at least you have all players participating in this gonzo brokeness to some degree.
So yes, I'm with you fighting the fight to get magic to a better place but in the meantime just add the dmn mythic martial.