I feel like Kled and Skaarl will end up turning into another Tank Fiora.

#1: His passive shield

It is a shield for 100% of your bonus health (which probably has some kind of base value) that can be refreshed with a few autos on a champion after Skaarl is scared away.

We know it isn't a lot of attacks from how, in the teamfight clip, Kled fills 66% of Skaarl's "Courage" meter with two basic attacks (though it might fill based on damage dealt, or based on your level, since we know almost nothing about that.)

Kled's health bar looked absurd in his clips, and that was when he only had ~1500 HP. Imagine how hard he will be to kill at 4.5k.

#2: His base damage

We don't know any specifics yet, but we do know that both his W and his Ultimate have % health damage. He might just end up building and still do an absurd amount of damage.

#3: His utility

Kled has a mini-hook on his mounted Q, and a cross between Galio E and Sivir Ult in his "Chaaaaaaaarge!!!".

Even if he doesn't build damage, he will be useful with these.