Not exactly. In fact, according to Dave Meltzer of the Wrestling Observer Newsletter, we might see Mysterio back with WWE earlier than originally expected.
Mysterio's WWE return had previously been penciled in for sometime in the early fall. He returned to the company as a surprise this past January during the Royal Rumble, and his in-ring performance coupled with the great crowd response enticed WWE into bringing him back long term. The sticking point has been what kind of schedule he would be expected to work as well as his ability to take outside bookings.
Meltzer speculated on Wrestling Observer Radio that Mysterio may now be back in time for SummerSlam, ahead of the previously planned pace. This is of course still contingent on WWE making an acceptable offer in terms of pay and dates expected to work in any WWE deal.
Mysterio's next match is not yet known, though with his match at Dominion Saturday night, it would seem like an obvious move for him to work the NJPW show scheduled for San Francisco's Cow Palace on July 7th. The company still has thousands of seats left unsold for the event, and an advertised appearance by Mysterio could certainly kick ticket sales into high gear.
The Cow Palace show really has had nothing booked for it yet specifically, with no stars or matches officially announced. Much of that was due to Dominion, the second biggest NJPW show of the year, taking place a few weeks prior and the company not wanting to tip their hand in regards to storylines following the big show. Expect matches to start being announced for San Francisco now very soon.
At Dominion, Mysterio teamed with Jushin "Thunder" Liger and Hiroshi Tanahashi to take on Marty Scurll, Adam "Hangman" Page, and Cody. The Bullet Club were victorious in the match and Cody commenced a post-match beatdown on Liger until Mysterio came in for the save.
Interestingly, Mysterio was supposed to wrestle Liger at Strong Style Evolved back in March in Long Beach, California but had to pull out of the match due to injury. They could always do that match in San Francisco since it never happened, or they could play off the ending of the Dominion match and have Mysterio face Cody. Either one would be a solid choice.