Boxing is nowhere near dead. Other than the pretty shitty heavyweight division, boxing is doing very well. Most MMA fans use the typical "I was a boxing fan until I saw the UFC" reason for not liking boxing. MMA will never completely take over boxing. From what I've noticed, the majority of MMA fans are very young and have had minimal exposure to boxing. But if you actually watch it, you'll quickly notice how most MMA fighters have unbelievably poor boxing skills compared to professional boxers. A guy like Chuck Liddell, with his awkward, looping punches, would be totally overwhelmed by a decent boxer in his weight class. Of course, the boxer would likely be beat fairly easily in an MMA match, but I think the boxer would have the better chance of crossing over into MMA than the other way around.
And the most exciting MMA fight doesn't even come close to the most exciting boxing match. Gatti/Ward I, II, and III and Corrales/Castillo I and II are examples of boxing matches that are vastly more entertaining than any MMA fight. You just don't get the long wars in MMA that you get in boxing. With the small gloves, it's one clean shot and that's it. I love both MMA and boxing, but it annoys me when MMA fans bash boxing.