I guess by "never leave again" he means he's just going to keep making occasional tv appearances like he was doing back in like 2004 after he'd stopped wrestling...apparently his contract ran out that time because Vince just completely forgot to renew it, which is pretty crazy.
As for doing another match, he's said he won't, but if they drive a truck of money up to his house I could see him doing at least one...it would be a more satisfying way to pay off this Cena thing (which has been going on for years since Cena started trashing him to the press to try to get noticed). Then again he tore his achilles tendon making some movie a while ago and I remember reading at the time that it would rule out any return to the ring, but plrenty of wrestlers have come back from such injuries (Austin breaking his neck sixteen times.)
So, in short, who knows!