First of all, regardless of the career implications, congratulations to Jeff Hardy and his girlfriend regarding expecting their first child.
This could really go in a couple of different ways. Perhaps he will want more time off more family reasons (if he isn't in jail) and the more relaxed schedule that TNA offers would likely allow him to have this. This would be tough for TNA in the short term if Jeff takes more time off, but let's face it, he's not exactly front and centre in a position of prominence these days anyway. But it would be good for them in the longer term as it may keep him associated with TNA for a longer period of time overall.
The flip side, though, is that job security and financial security may become more significant for him and his expanding family. He might be lured back to the world of WWE (if Vince would take him back, which I imagine he would) where the money, I assume, is significantly better and his job stability would be better because the organization itself is more stable. You never really have job security in TNA because that company is in peril and would be far more likely to fold than WWE. And the strictness of the drug policy of WWE, a deterrent at the moment because he seems to like the relaxed drug policy of TNA, might be more appealing to him later as a family man with different priorities and perspectives.
I hope scenario 2 happens, because I would like to see him end his career in a WWE ring. Plus, I worry about Hardy's future if he remains with TNA. His life and career seems to be somewhat in a tailspin at the moment, it could be better for him overall to be back in the structure of WWE, otherwise his career (and life) may end prematurely.