I think you are still confusing the Combat Challenge and the Combat Superiority class features.
For the sake of clarity, let's get the relevant rules up here in the post (bolds added by me):
Combat Challenge
In combat, it’s dangerous to ignore a fighter. Every
time you attack an enemy, whether the attack hits or
misses, you can choose to mark that target. The mark
lasts until the end of your next turn. While a target
is marked, it takes a –2 penalty to attack rolls for any
attack that doesn’t include you as a target. A creature
can be subject to only one mark at a time. A new mark
supersedes a mark that was already in place.
In addition, whenever a marked enemy that is
adjacent to you shifts or makes an attack that does not
include you, you can make a melee basic attack against
that enemy as an immediate interrupt. PHB pg76
Combat Superiority
You gain a bonus to opportunity attacks equal to your
Wisdom modifier. An enemy struck by your opportunity
attack stops moving, if a move provoked the
attack. If it still has actions remaining, it can use them
to resume moving. PHB pg76
IMMEDIATE ACTION
✦ Trigger: Each immediate action—usually a
power—defines its specific trigger. The one type of
immediate action that every combatant can take is a
readied action (see “Ready an Action,” page 291).
✦ Once per Round: You can take only one immediate
action per round, either an immediate interrupt
or an immediate reaction. If you haven’t taken an
immediate action since the end of your last turn, you
can take one when a trigger allows you to. You can’t
take an immediate action on your own turn.
✦ Interrupt: An immediate interrupt lets you jump
in when a certain trigger condition arises, acting
before the trigger resolves. If an interrupt invalidates
a triggering action, that action is lost. For example,
an enemy makes a melee attack against you, but you
use a power that lets you shift away as an immediate
interrupt. If your enemy can no longer reach you, the
enemy’s attack action is lost. PHB pg268
OPPORTUNITY ACTION
✦ Trigger: Opportunity actions allow you to take an
action in response to an enemy letting its guard
down. The one type of opportunity action that every
combatant can take is an opportunity attack (page
290). Opportunity attacks are triggered by an enemy
leaving a square adjacent to you or by an adjacent
enemy making a ranged attack or an area attack.
✦ Once per Combatant’s Turn: You can take no
more than one opportunity action on each other
combatant’s turn. You can’t take an opportunity
action on your own turn. PHB pg268
In your scenario, the Kobolds are all marked, and they shift. This activates Combat Challenge (ref above). Since Combat Challenge is an immediate interrupt (also above) it is limited to only once per round, as per the rules, so he would get to smack only one creature, even if they all shifted.
Now if the kobolds had all moved, this would draw an Opportunity Attack, which is once per Combatant's turn. So as each kobold moves, it would be hit by an Opportunity Attack, which activates Combat Superiority.
So, at most, with all 8 kobolds marked and surrounding him, the theoretical maximum would be 9 attacks by the fighter, not 16. Even if the fighter nailed a moving kobold, the kobold could just use another move action and keep moving, as per RAW of Combat Superiority, so although a fighter is sticky, he's not the permanent boat anchor you are imagining him out to be
I hope this clears things up!