I think Vince's pride would get in the way of him just selling it. He broke his back trying to make WWE great. He had to file for bankruptcy when Stephanie was born to make ends meet. The only way I think he would sell it was if he thought it was too far downhill with no upswing in sight.
He is getting old though with rumours of his eyesight failing. IDK how reliable they are. He might just be putting it out there that he is open to offers if one was very stupidly high (1 billion +?)