Last week, Hangman Adam Page seemingly buried the hatchet with Matt Nick Jackson and are moving towards becoming friends again so it's possible that he will be the person teaming with them next week.
However, the name that seems more likely is Kenny Omega. Dave Meltzer reported over the weekend that the reason why The Bucks vs. FTR is not happening at All Out is that the company wanted to have The Bucks involved with Page and the returning Kenny Omega.
With less than 4 weeks left for All Out pay-per-view, it seems very possible that Omega will be back next week. Sean Ross Sapp reported several weeks ago that Omega was being talked about for a match at All Out.
Here are the brackets for the AEW Trios Tournament:
-Death Triangle vs. Will Ospreay & Aussie Open
-Andrade, Rush & Dragon Lee vs. Young Bucks & TBA
-House of Black vs. Dark Order
-Best Friends vs. Trustbusters
UPDATE: Later in the show, Hangman Page told The Young Bucks that he can't team with them next week because he will be supporting The Dark Order.