While I agree Kennedy has a lot of potential, I don't believe he's a sure fire main event wrestler. He certainly ranks among the top 5 in the WWE as far as mic skills go, but he needs to refine his wrestling before he's pushed to the next level. At least in my opinion, he moves awkwardly around the ring and his matches are poorly paced. They just don't seem to have a flow to me. Also, he needs to refine his move set to a degree. He hasn't really been given any finishers he can pull of seamlessly.
I also don't think he'd receive a huge push if he went to TNA. While he's established himself as an upper mid-carder in the WWE and is certainly over, I don't believe those credentials would put him over established stars like Sting, Kurt Angle, and Booker T. He definitely would have a shot at someday being TNA champ, but not within his first year or two there.
Kennedy is still a talent in development, albeit one with a tremendous amount of potential. If he can stay injury free long enough to have some consistent time in the ring, there is no doubt he can be a main event wrestler someday. However, if he keeps finding himself injured at such constant rate, he'll never reach these expectations. I honestly wouldn't be surprised to see the WWE not sign him once his contract is up. He has been given at least two huge opportunities that's he managed to screw up with an injury and suspension (MITB and Vince's son angle). The WWE can only nurture someone for so long.
I expect a lot of dissenting opinions, and that's fine. But bear in mind, I've been watching wrestling for just about 20 years. I realize that wrestling evolves and that things aren't the same as they were say even 5 years ago. So, I'm not basing my opinion on comparisons with dated product. I'd just appreciate it if someone gives a dissenting opinion, they don't follow it up with "you're stupid" or "I've been watching wrestling for 2 years and you don't know what you're talking about." I've seen plenty of stars come and go, guys who everyone thought would be the next big thing and fizzled out, as well as guys who clawed their way up to the top.