But it is certain that King only loses it in his hybrid form? According to the spoilers, King actively trades dura and speed depending on his fire. And at the end, of course King is still extremely tough without his hax, that's clear.
Marco's fire isn't necessarily superior to King's - in Prometheus' case, I recall Marco's fire was that effective because of the life energy. But let's see.
If King is truly done, without showing COC and awakening, knowing that there's a timeframe in which King is more vulnerable to attacks when his fire is deactivated, I do believe his RHM counterparts can match him quite well with their skillset. At the end, I still believe King's the strongest of them - bar Shiryu and Beckmann - but the gap isn't large. It's definitely not high diff, let alone mid diff imo.
What do you think about that?