The Olympic event for Overwatch was annoying in that the loot box situation was pretty unforgiving, urging players to buy more boxes, but it was at least a fun influx of new cosmetic content for the game.
It seems we are about to get another one too. This hasn't been confirmed by Blizzard, but an image for a purchasable Halloween loot box, ripped from the Xbox Store has turned up on Reddit. There is no indication of how the event will work, but nothing in the description suggests it will be any different to how the Olympic one worked.
Of course this isn't confirmed, so take it with a pinch of salt, but this would seem to make sense. Lots of new cosmetic items in Overwatch is great. Visual diversity in characters is fun! Hopefully it won't be so reliant on luck and buying more boxes to get what you want this time.
I am expecting to hear something soon.