You need to research Some real world data. looking at that Hornady load data tells you very little if anything about what a cartridge is actually capable of. Just look at the actual charge weights associated with each powder. Most books are very conservative in their numbers, especially for older cartridges like the 300WM. In my experience and from what all I have read the 300 PRC can get close to the 300 WM but no where near 150-200 FPS faster. Is it a good round? Yes. Is it better than the 300 WM? No. It may have some things going for it (seating depth, no Belt, possible a bit more efficient(?)) but the 300 WM can Be more potent in a similar platform.
On the 300 WM fading into the Sunset, there is no way in H-E double hockey stickers that will ever happen! There are hundreds if not a thousand plus times as many 300 WM out there over the 300 PRC. An FYI, I grew up with a 300 WM. I built two 300 PRCs as it was my dream cartridge design I always imagined right between a 300 WSM and a 300 RUM. They where decent but finicky with loads and didn't exceed my expectations. One went down the road and the other was turned into a 300 WM and I could not be happier with going back to my 300 WM. A properly set up 300 win mag can not be over-shadowed by the PRC. I don't mean to come off as a Richard.