Viewership is already ahead of hockey and is on track to overtake every American sport except NFL by 2020. It was the first worlds final to go to five games but for the rest of us it's hard to follow. The commentary is interesting with each gamer having their own call signs such as Blank and Wolf. Most millennials relate more to these gamers than to professional sports stars.
It's a great business model change for gaming companies. Gaming in general is predicted to increase significantly (see chart below) so far they earn money from games but if you begin to add in ticket sales, sponsorships and licensing revenue its financially looking much more attractive than the traditional sports model.