Water is wet and Fortnite will indeed continue being a black hole, sucking every big ticket property within it. This time around, the notoriously stacked lineup of Fortnite seems to be adding Ryu and Chun Li from Street Fighter, not Mortal Kombat.
According to Fortnite leaker ShiinaBR, a “Skirmish” event was being teased in-game via a portal that began opening on the map. While folks seemed to have believed this would be the beginning of a WandaVision crossover, portal images that ShiinaBR was able to find instead pointed to a crossover with Street Fighter.
The images in question seem to show Suzaku Castle, a classic Street Fighter stage that's widely considered the home stage of its most famous character, Ryu. The stage was even brought over to Super Smash Bros. when Ryu was added to that game as DLC. ShiinaBR also found audio files that sounded like a distant and slightly distorted version of Ryu's theme.
Lucas7yoshi, another Fortnite leaker, found the actual portal on the map, which shows a static image of Suzaku Castle within it and can actually be found in the game. Over at Gamespot, they were able to replicate the portal appearing, so the in-game teases seem to be ramping up for an eventual announcement.
Since these initial finds, a virtual dam of Street Fighter secrets has burst wide the hell open. Dataminers have been able to find the announcement trailer, which shows the Fortnite guy “Jonesy” interrupting a fight between Chun Li and Ryu to bring them to Fortnite. This falls in line with what the character has done to explain so many of the crossover characters this season. A video of the character's emotes have also found their way online and show off Chun Li's iconic Lightning Kick and Ryu's Shoryuken.
A promotional image showing announcing Chun Li and Ryu’s availability in-game seems to have leaked as well. The image appears in the vein of the same leaks that occurred around the release of Kratos and Master Chief skins earlier in the beginning of this crossover season. We should expect a confirmation of the crossover soon given how thoroughly it’s leaked by this point.