Lesnar Returning to WWE?

I've been having an argument with my friend about this for a long time. He 110% believes Lesnar is coming back to the WWE after his UFC contract is up. I don't think Lesnar is leaving, but he keeps on telling me that Lesnar and Goldberg (Yeah I Know) are facing off a Wrestlemania 28. I want this to finally end, so I need to know what's going on.