In a recent Developer Update, Jeff Kaplan commented on Overwatch's success over the year, and made remarks about some of what we can expect for next year. Regarding the several seasonal events that have taken place over the year, namely the Summer Games, Halloween Terror, and Winter Wonderland events, he stated that Blizzard is very pleased with the mostly positive feedback on each event, and is glad that fans enjoy the new and unique content they bring as much as the development team enjoys making them.
Previously, Blizzard did comment on some slightly negative response about the Winter Wonderland event, though. Namely, many people expressed disappointment over Mei's Legendary skin for the Winter Event, with many feeling it underwhelming and not different enough from her standard outfit.
Jeff Kaplan responded directly to this, stating, "Sorry you are disappointed with Mei’s winter skin. We don’t have a specific rule for what makes something Legendary or Epic. We just sort of make a gut call based off of what we think is cool. Coolness is very subjective, and based off of the community reaction it seems like our gauge was off on this one...It’s all good feedback and we’re learning something for future events."
Blizzard has usually been on point in the eyes of the majority when it comes to their skin creation, though certain characters are infamous for their lack of quality rare skins, such as Zarya or Tracer. This is the first official response from Blizzard over outcry over a particularly low quality skin, though, and it seems they'll be taking it to heart for the future.
More recently, in the Developer Update just released, Jeff Kaplan made comments on content we can expect to see be added next year. He stated that Blizzard currently has multiple heroes in the works, but that it is likely that not all of them will be finished due to the amount of work and testing that goes into making sure everything is properly balanced. One character in particular is very far along in development, however, and it is very likely that this character will see an official release, though Kaplan did not make any specific comments about them.
An area that will be receiving an upgrade very soon is the ""Emote Wheel" that allows you to say things like "Hello" and "Group up" to your teammates. Kaplan stated that they are planning on adding further customization to the wheel soon next year, and one of these upgrades comes in the form of allowing people to set four custom voice lines instead of just one.
Other changes Kaplan commented on are mostly minor, but still beneficial nonetheless. Like the option to select up to four voice lines, players will soon be able to select up to four emotes to go into battle with at once, which I personally have been hoping for for awhile now, a sometimes one emote just doesn't really cut it. Also similarly, players will be able to bring four sprays with them instead of just one, although only one of these sprays may be placed per player at a time.
Jeff Kaplan also referenced the upcoming map, Oasis, that has been in testing for a time now, and stated that more maps are currently being worked on and tested, though similarly to characters, some of these will likely never be released. One map in particular is also entering the final stages of testing, and while it is a map using a traditional game mode, Kaplan stated the team is open to introducing maps with brand new game modes at some point in the future.