From what I understand, the rumor is that Panasonic will debut the HDV version of the DVX100. It will still be 24p, but in an HDV recording format. WHat this says about the future of HDV is anyone's guess at this point, but I think signs are showing a more gradual changeover to HD than people (especially the SMPTE) originally anticipated. The camera is rumored to be priced around $10,000.
As far as renting equipment, I think it depends on what you're doing with the gear. If you buy a DVX100 and use it everyday professionally, and are making money with it, it should pay for itself rather quickly (especially with such a high demand for it). And the technology is not becoming obsolete so fast that the gear is rendered completely useless 6 months later. I still use my Sony TRV-900 for many applications, and that was one of sony's first prosumer digital video camcorders.
If you're going to buy a camera over $2000, but you won't use it a) to make money or b) on a regular basis, then yes, it's better to rent on a per project basis.
These are all the factors that professionals take into account every day. It's also why most event and corporate videographers own equipment, whereas high end cinematographers rent their packages.
-Chris