Even though he has said we’d see it later this year in the past, there is more confirmation from Kevin Feige himself that we will have a look at Avengers 4 before the end of this year.
Last night there was a special screening of Black Panther for potential Oscar voters, and people were able to ask him questions. In addition to saying that they’re still undecided on Namor in the MCU and that Guardians 3 is on hold, he confirmed the Avengers 4 trailer:
If they release the Avengers 4 trailer around the same time as the Infinity War trailer, it’ll most likely be at the very end on November or possibly early December. So at best, we’re probably about a month away!