There's no way TNA's "major" singing is Goldberg. TNA has already got their storylines for the next few months planned out and it's obvious to anybody watching that AJ Styles will win the Bound For Glory series this year and take the belt off Bully Ray in October. If Goldberg was coming in then he wouldn't do it unless he was getting a world title run which isn't in the plan for TNA. One thing TNA has been doing well over the last year and a half is letting storylines unfold and play out over the course of a number of months. Goldberg coming in would fuck up everything they've been doing recently and since Vince Russo doesn't book shows for them anymore there's no chance they're just gonna throw everything they planned out the window for Goldberg's 47 year old has been ass.
I wouldn't worry about TNA's rating's being low. They're still the most watched show on Spike TV. As long as Spike is around TNA will always have a TV show. Plus, both TNA and WWE have had dips in the rating's the last several weeks because of the NBA and NHL playoffs. I'm not surprised TNA got such a low rating this week since it was going up against game 4 of Heat/Pacers and it wasn't that good of show. It was the go home show for the PPV tomorrow so not much happened but last minute selling for the PPV.