It is going to be a special day for sure, but those talking to expect an update are creating expectations without any basis for them. This could only lead to disappointment if expectations are not met. My advise is to not expect anything and just take things as they come.
The only thing official is the anniversary date itself. Hello Games have not announced a party, the community has. The main event/party is done by NMS10, see: Announcements: NMS 10 Year Anniversary
I am sure various communities will have organised their own festivities as well. There is also going to be another ‘live’ meetup in a pub in Guildford August 26th. So all in all, everyone is going to be celebrating, rightfully so, but nothing ‘official’ that I am aware of.