17H2
It's already going "poof!"
I don't think the 17 HM2 is going anywhere for while yet. Steve Hornady was asked point blank at the last SHOT show about it's future, and he stated that Hornady will NOT be walking away from the cartridge. Hornady has invested a lot of resources in the .17 HM2, and while ammuntion sales have been not what they had hoped originally, it's sales have been improving.
The cartridge has found a firm place and following with squirrel hunters, who say it's the perfect choice for what they do. The 17HMR is too powerful, the .22LR not quite enough, but the Mach2 fits the bill perfectly between the two. Great accuracy, longer range than the .22LR, and low report.
I can imagine squirrel hunters are a small minority, but they are a vocal one. My guess is Savage will chamber rifles in 17 HM2 for a long time to come. As far as I know, CZ is the only other manufacturer chambering it.
What hurt the cartridge most was Ruger's refusal or inability to offer the 10/22 in 17 HM2. Had they done that, chances are it would have taken off in popularity much more than what it did.
Companies like EABCO are selling a pile 10/22 17 HM2 coversion kits, it's one of their most popular items.......