To be competitive in today's market, a new lever gun would need to have some benefits besides the lever. It used to be that they were lighter, and handier for hunting, and much easier to carry. That is not so true these days since you can find scoped bolt guns anywhere that are lighter, and just as fast into action. Hunters now shoot more from stands, and that makes the slightly faster second shot less important. If the gun is slimmer, better balanced, accurate enough for hunting, and esthetically pleasing in a traditional way then it will sell. Caliber is secondary. So far, no long range lever gun has every succeeded in a big way. Ammo costs, and availability is an often overlooked issue by marketing folks, and manufacturers too. I think that is one reason the 30-30 just keeps chugging along. Of course it gets the job done in a fine manner too. I really see no point in long action calibers for lever guns. Why? I see a need to produce one that is more under 8 pounds scoped though. I really like Marlins, but a 30-30 336 feels like a brick beside a Kimber bolt gun. Calibers? Well, if you insist, a .308 will do the job on anything you don't want a big bore for, and a 250 Savage / .243 will take care of the other end. OK, a .223 if you insist on making another size bolt face, and feed system.