Suffice to say, WWE noticed the massive reaction that Mysterio received that night and have been working to re-sign the former world champion and legendary luchador. That signing will likely have to wait, at minimum, a few months, as Mysterio is set to wrestle Jushin "Thunder" Liger during New Japan Pro Wrestling's big show in Long Beach, California at the end of March.
However, the Wrestling Observer's Dave Meltzer notes that expectations within WWE are that Mysterio will indeed be signed by the company once again. As of right now, most at WWE expect the signing to come sometime in 2019, though there is an outside chance it may come about this year.
The deal that WWE is considering for Mysterio is reportedly something along the lines of what WWE has worked out with Chris Jericho in the past. In essence, Mysterio would work a series of short, part-time stints with the company under the deal and still have the freedom to freelance on his own outside of WWE and continue to work on other projects he is interested in.
There's no doubt that Jericho's freedom has been almost unprecedented when it comes to WWE, though that was a bit of a surprise as nobody ever expected him to wrestle anywhere but WWE. New Japan Pro Wrestling is the second biggest promotion in the world, with its eyes set toward North American expansion in the days ahead, so seeing Jericho work there this past January while having been off from WWE since the summer had to be a shock for many that are employed by Vince McMahon's company.
While the Mysterio deal being worked on is indeed reported to allow him some outside freedom, nobody knows for sure if they will allow him to wrestle for outside companies as well. Jericho had noted that Vince McMahon encouraged him to wrestle Kenny Omega at WrestleKingdom this year, and Jericho was brought for the big RAW 25th anniversary show just a few weeks later. Would they allow Msyterio the same freedom?
Mysterio is someone who can earn a lot of money freelancing for other promotions, so if he is only working part time for WWE, that's likely an option he will want. Time will tell on if the company will sign off on that.