Here's how I'd book Jericho for 2018
Omega at Wrestle Kingdom 12, Kenny goes over obviously.
Jericho returns at the Royal Rumble later in the month. Gets eliminated by Nakamura.
On a SD, Nakamura vs Jericho gets booked. Nakamura wins, then Jericho turns heel destroying Nakamura.
At the next PPV, Jericho gets a win over Nakamura. Setting up a rubber match at Mania.
In one of the main events of the show, Nakamura beats Jericho.
Jericho goes on hiatus again.
Returns to NJPW in June, at the Dominion show Jericho announces he will be entering the G-1 Climax.
Jericho wins his block in G-1 getting wins over Tanahashi and Okada. But loses in the final to Omega again.
Jericho then appears back in WWE returning at Summerslam, staying through the year having feuds with Brock and Bálor.