I don't know any commercial photographers that want or need to shoot 26000 ISO or above. Yeah, it's nice to see Canon advancing ISO performance, but it's now more of a marketing function that something pro photogs can actually use.
If an ISO setting gives clean enough images, then a commercial wildlife photographer will welcome as much sensitivity they can get. Mostly, they prefer natural light over flash, so it would extend the period into which they can shoot. Imagine being able to photograph crepuscular wildlife after the sun has set or even into almost pitch black and still get detail. It isn't yet possible, but wildlife photographers would welcome the opportunity.
This shot for example was taken well after sunset at ISO 1600. At the moment, only silhouettes are possible (even with a D3 - I've seen similar results from that camera). It shows behaviour that only occurs after sunset and a flash is useless, but imagine a clean image that could capture detail instread of a silhouette.
Roding Woodcock by Kernuak, on Flickr