I'm going to chime in here and put my 2 cents in. First off let me start off by saying I'm excited for this cartridge. Having said that, yes there's other cartridges that are similar and more capable than the 7mm PRC will be. It looks to be a ballistic twin to the 7mm WSM and 7mm Rem Mag. However, this is designed to be a long range cartridge from the go just like the other PRC cartridges. Yes you can build your 7mm SAUM or WSM on a long action and run 0.200-.240 freebore with 168-180s at the same speed as the PRC. However, you have to build the rifle, order the reamer spec'd to work with the heavy bullets, and deal with the fact that no one supports either one of those cartridges anymore other than a couple brass manufacturers. No factory rifle, no factory ammo, and they're essentially a wildcat with the multitude of modified chambers out there to make them equal the 7 PRC. Yes there's the 7mm Rem Mag, but it's the same way, the SAAMI specs for it were never designed for long range, heavy for caliber, modern high BC bullets. You can make it work with those bullets with a fast twist barrel and handloads, but the average hunter who doesn't have a custom rifle and doesn't reload can't get that level of performance.
Now in steps the 7mm PRC. Whether it's a copy cat or a knock off, you can't dispute the fact that Hornady supports their cartridges as good or better than any other. They have the dies, the brass, the ammo, and they design them for modern bullets with a modern case design. Yes the PRC chambers have clicker issues, but it's fixable and doesn't matter for the vast majority of the market who just buy factory ammo. Factory rifle manufacturers pick up on the PRCs because they're good cartridges and bring a lot to the average guy who previously had to either build a custom rifle and handload or just deal with the fact they couldn't get near the performance as those custom rifles and custom handloads. I still think custom rifles and handloads are always the best solution, but cartridges like the PRC in quality factory rifles bridge the gap better than before.
I'm not denying how good the current cartridges are ie 7mm Blaser, 7mm WSM, 7mm SAUM, 7mm RM, etc. My opinion is I think Hornady took all of them into consideration and designed what they believe is a solid 7mm cartridge for long range shooting. It's not too overbore, but still gets 180 class bullets near 3000fps. There will be components, ammo, rifles, etc available for it and will be very well supported. That can't be said for some other cartridges. Looking at the 7mm PRCs siblings the 6.5 and 300, I bet Lapua, ADG, and Peterson will have brass available for it within 2 years of its release. So all in all, I think it's a good cartridge and will be very popular and successful for many reasons just like most of Hornady's cartridges. This is what the SAUM, WSM, Rem Mag etc should be but the market and technology was much different in their time of release.