#1 Rusev's unclear future
The biggest reason why WWE has booked Shinsuke Nakamura to be the next challenger for the Intercontinental Championship is that the Creative team wants the King of Strong Style back in the singles division. Nakamura had joined the tag team division of SmackDown Live earlier this year. The Japanese Superstar joined forces with Rusev and the team even competed for the tag team titles at WrestleMania 35.
They fought a few matches post The Show of Shows, with their last televised match taking place on 16th April.
The fact that SmackDown's tag team division is in dire need of tag teams, yet the company has booked Nakamura to return to the singles division indicates that something is wrong with the former NXT champion's tag team partner.
Rusev has taken a lot of jabs on WWE on Twitter and even Dave Meltzer recently stated that he won't be surprised if the Bulgarian Brute leaves WWE soon.
Thus, WWE has booked this feud just to bring The Artist back in the singles division, and booking him in a title feud with someone like Finn Balor is the best way of doing so.