John Cena's WrestleMania 34 plans don't seem to involve the Smackdown brand.
Following this Sunday's Fastlane pay-per-view, Cena is not scheduled for any SmackDown Live tapings. He's not scheduled for tonight's SmackDown Live at the Resch Center in Green Bay, WI, and the only upcoming live events he's currently slated to appear at are for the RAW brand.
The last date on Cena's current WWE schedule is the post-WrestleMania episode of Monday Night RAW in New Orleans. Cena was not featured in recent advertising materials for SummerSlam in August or The Survivor Series in November, although he could be appearing at those shows if his schedule opens up during those periods.
Cena's next major movie, Blockers, is scheduled to be released on April 6th, days before WrestleMania 34. He is rumored to be facing The Undertaker at WrestleMania, which would be their first singles match on pay-per-view since Taker defeated Cena at the Vengeance pay-per-view on July 27, 2003.