Source: The Wrestling Observer Newsletter
According to sources, Rey Mysterio's current WWE contract will expire later this month and he hasn't signed a new deal as of this writing. It should be noted that many people now expect to see him re-sign with the company but under a deal that allows him to work limited dates.
The company also wants to use him as a brand ambassador for Latin America. He's pretty much been doing this as of late anyways as he's been overseas promoting WWE.