To heck with the 5mm, give me a .25 Stevens rimfire. 60-65 gr pill at 1100- 1200 fps from a handgun, 1800-1900 from a rifle. E. Keith was right about this one. People dropped the ball on it.
For centerfire.......... Ruger needs to bring back the .32H&R in their Single Six and to keep with the rifle forum Marlin needs to bring back it's lever gun in that chambering. I like the idea of the .250 Savage and will add another not quite dead cartridge, the .222 Rem. Glad Savage is now chambering it in their 25.