I think we should plan for worst case scenarios. First best worse case scenario; Overwatch 2 gets delayed until spring 2021. In order to keep the hype for Blizz con 2020 they decide to release the next hero at Blizz con itself rather than in the spring or summer. Remember we are only getting 1 hero before Overwatch 2 so if it gets delayed the hero will be delayed as well.
I think the above scenario is VERY likely. However it gets worse, much worse… what if it looks like Overwatch 2 will be delayed until summer or autumn 2021? Again, quite plausible. You are only getting 1 hero because that is all you deserve but should they be released in 2020 at Blizzcon? No. Not if Blizz have Diablo 4 or some other game that can carry the slack. Then there will be no hero. You will get nothing for the entirety of the year!
We need to brace ourselves for this eventuality.