According to the website, all star weekend is 3 days long (Aug 10-12, Fri-Sun), and this makes me believe that it will be more than just one match.
I can imagine all kinds of goofy things they can do like Lucio sprint, Winston jumping contest to moving targets, Soldier Frogger (successfully crossing roads with obstacles like the cars in the Oasis map), Junkrat cornhole, etc. They can also utilize some of the arcade modes (death match, mystery duel, lockout elimination, mystery heroes, total mayhem, etc.) and the event modes (Lucio ball, Junkenstein's revenge, Mei's snowball offensive, Capture the rooster, Overwatch uprising). But I think most people will only care about the ones that has meaningful relevance to real in-game skills. After all, the hype of the all star weekend should be about who really are the best players (on each hero or role) in the league.
I think they should utilize some of the arcade modes, so this event can promote more people to enjoy the arcade modes, but utilize it in a way that has meaningful relevance to real in-game skills. And maybe have one real game with all star teams each day as a main event.
Friday, August 10th: Challenge the Champion
- Capture the Flag between OWL Champion vs. All-Star team - Just for fun mainly. Also, I think this is one mode where you need to think about both defense and attack. So it will be interesting to see how pros strategize it.
- 6V6 Lockout Elimination - Let's see how well they can build up diverse comps!
- 6V6 Mystery Heroes - To see how flexible the star players in the Champion team and the All-Star team are
- Bo5 Match between the OWL Season 1 Champion vs. All-Stars from the rest of the teams (max 2 players from one team)
Saturady, August 11th: Battle to rise as the top individual
- Death match of 8 most voted DPS players
- Widow Headshot only match (like https://www.youtube.com/watch?v=PMiU-3DOw0I)
- McCree Headshot only match (like https://www.youtube.com/watch?v=Tpe2qmIG3WI)
- 1V1 Mystery Duel with only DPS heroes (or some modification of it, like Tracer tourney, Genji tourney, hit-scan tourney, etc.)
- 1V1 Mystery Duel with only Tank heroes
- 1V1 Mystery Duel with only Support heroes
- 3V3 Elimination match (one player only with DPS heroes, one player only with Tank heroes, one player only with support heroes)
Sunday, August 12th: Battle of the Division All Stars
- Team death match of Atlantic All-Stars vs. Pacific All-Stars
- 6V6 Mystery Heroes
- Bo5 Match between Atlantic Division All-Star vs. Pacific Division All-Star (max 2 players from one team)