With the multi-purpose Deebo Samuel set to miss this game, Brock Purdy and the Niners will likely look to Brandon Aiyuk -- who has taken on the more traditional role of a WR1 the past couple of years following Deebo's role expanding past the receiver position -- even more to be a reliable target in the passing game.
The good news for San Fran and their San Fans is that Aiyuk is a very solid WR1 and has proven that he can be explosive, just look at his outings against the Steelers and Cardinals earlier this season. In those two games, he was targeted a combined 14 times, catching all 14 targets for 278 yards and a pair of touchdowns (though, both of those came against Pittsburgh). While he hasn't found the end zone since Week 1, he has been a solid option for picking up yards and is on pace for the best season of his career.
The good news for Cincy is that outside of Aiyuk (and Samuel but, again, he's injured) there really aren't any other wide receivers on the 49ers' depth chart worth losing sleep over. They have a couple of solid contributors, like Jauan Jennings and Ray-Ray McCloud, but no one who will likely go off and have a huge game. Not to mention Cam Taylor-Britt is really blossoming in his second season and D.J. Turner II has turned out to be a really good pick.
I have complete faith that those two can stop or at least limit Aiyuk, but if they struggle and have a bad day? It might get ugly for the Bengals.