If his surgery goes well (hopefully), then surely his drawing will get better, or faster, or both.
But other than that, he now has a month to think about his story without being able to draw it. That means he'll have more time to think, and plan the story better, so I expect the story to be a little better when he returns.
Besides, I think it takes about... 3 weeks? from the moment Oda is working on a chapter until it is being published (drawing assistants, editor...) so I think Oda had already taken the surjery about 3 weeks before his message was published, and they waited until all of the chapters that were ready for the next stage were published before they announced his surgery to the fans. This way they'll know already if the surgery succeeded (probably did, or else they'd give him more time to recover), and it means that in the coming week or so he'll already be able to start working on chapter 1087.