Huge, intimidating, and full of charisma.
And this can't be fulfilled by anyone else currently in professional wrestling? Not true, not at all.
First of all, I'll admit that I'm a big Triple H mark, and I'll definitely agree that WWE without him would be quite a lackluster due to the sheer importance and impact he's had on WWE over the past 10 years.
Triple H is a big star, and he'll be sourly missed when he does disappear, however he's not the last great superstar that WWE has produced, or ever will produce.
John Cena is probably the closest we can get to it right now, at least of truly established people (Because I'll gladly hang my hat on Sheamus having the potential to be a truly great superstar 3-5 years down the road). John Cena, much like Triple H is a beast of a man in terms of build, he's intimidating to be in the ring with just looking at the sheer amount of muscles he has, as well as the sheer power behind his wrestling style (-->http://www.youtube.com/watch?v=r5nxt2Z0MZs<---) as well as his charisma is almost, if not completely unparalleled in todays WWE. John Cena is able to make the crowd go absolutely insane, in boos or cheers it doesn't matter, because in the end of the day, he gets a reaction. John Cena is able to put on great matches, some might even say greater matches than Triple H, and to some extend I tend to agree with some of the choices of John Cena matches being said to be better than Triple H's top matches.
John Cena will go down as one of the greatest WWE superstars, and it won't be due to the fact that he could hang his hat on being a top talent, and top draw of WWE for many years, no it'll also be due to the fact that John Cena is one of the few ultimate packages. Sure he's not Bret Hart in the ring, but he gets by with what he has, and puts on great matches on a regular basic. He has a great energy on the microphone that I would say might even outdo The Rock (Yes, I said that, outdo The Rock, I said it again, it's not an error people!) and maybe even Ric Flair and Roddy Pipers energy and intensity. John Cena has a great flow with words, something he proved this past RAW, as well as many many times in the past with his raps as well as general promos. The man just oozes charisma.
Overall, Triple H is a great, great superstar, there's no denying that. He might easily rank among the top 10 or 20 greatest of all time, at least if you ask me. However, to say that Triple H is the last great superstar, is quite frankly, bullshit.