Okay just clarify in the beginning, hero pools WILL REMAIN in Overwatch League, just not in Competitive Mode.
On to the exciting news- or not so exciting news for some- Overwatch will be removing hero pools for competitive play. Now all of those one tricks will be able to play their character without restrictions. I mean aside from the random nerfs and reworks that tend to anger us all.

Community Manager Molly Fender said in a post to the official Overwatch forum:
“We’ve been listening to your feedback and constantly iterating on the feature behind the scenes. We initially implemented Hero Pools to address issues with stagnating metas and to keep match-ups exciting and fresh. However, we’ve found that the introduction of Experimental Card and increased hero balance updates has helped us work towards a healthy, changing meta in Competitive Play without needing to disable heroes.”
It has been definitely been a journey since the introduction of hero pools in January. We have watched various heroes removed multiple times, while others were constantly available and there was some confusion. Don’t forget about the week that two supports were removed when there is only seven to choose from. Is this a positive thing that will be happening to the Overwatch competitive world? We will see, but at this moment there is no hero pools set to return in any given date in the future.
Starting Saturday, we will see the beginning of a new hero pool rotation. Rotations will make an appearance for the first two weeks of the Overwatch League tournament cycle. For more details on how this will work, go check out the website here.