Is it just a storyline, or has his contract ended and that was how they've written it in to the show? Or to simply put it, have TNA and Hogan parted ways?
If he is gone, TNA might move on. If not, when he returns it becomes all about him again. I think it's about time TNA moves on and develops it's own characters.
Currently AJ has a bit more to him, Magnus is on the road to either a heel turn, or a world title after the Sting match and his character is developing well. Then Dixie herself is developing as a character, based on reality, which seems the current trend. (she gets criticised alot and is using that as the motivation for her heel actions)
If they can sort out a few more main event characters, and keep up the big name X division matches. They could get back on track. Not sure how they will draw around the US without Hogan, but they can always go back to the studio style arena again.