Fortnite update v8.10 has sparked a bit of confusion. On top of adding hamster balls and one-shot weapon vending machines, the update made some changes to the way Fortnite Battle Royale cross-play is handled. Where PS4, Xbox One, and Nintendo Switch players were previously grouped together, PS4 and Xbox One players are now in one group while Switch and mobile players are in another.
This means Switch players will automatically matchmake with mobile players and other Switch players. However, it doesn't mean Switch players can no longer play with PS4 and Xbox One folks. To do so, they'll just need to party up, similar to the way mobile and PC players will only play with each other if they're in a cross-play party.
The "motivating factor" behind this change was "unlocking optimization potential allowing us to run more playlists during more hours of the day while supporting more data center locations," Epic said in the patch notes. In other words, Switch and mobile Fortnite players now have their own server ecosystem because - presumably due to their player populations or their in-game performance - it's more efficient to put them together rather than lump Switch in with PS4 and Xbox One.
"We expect an on-average better per-game experience for both mobile and Switch players," Epic said.
Just to be safe, I've reached out to Epic for clarification, but Switch players have reported playing with PS4 and Xbox One folks just fine after the update. So if you play Fortnite on Switch, rest assured that, yes, you can still party up with your PS4 and Xbox One friends. (Update: Epic confirmed that "you can party up with players on other platforms and they can all play together. No change there.")
It's never too early to start thinking about Fortnite Season 9.