I wouldn't expect any new dual-tuner models to come out; there is no need now that Genie is widely available. DirecTV is in replacement mode for the dual-tuner DVRs. I had an HR21 go out last week (hard drive failure). My daughter was a bit disappointed to lose whatever silly shows she had recorded on their, but at least I have a list from the Series Manager from a month or so ago. DirecTV replaced it with an HR24. I also have an HR23 and an HR34 in my system.
Something to keep in mind is that DirecTV has two interfaces available, their own and TiVo, which has several enhancements not available on the standard boxes. While the TiVo interface has it's own issues, I wouldn't be surprised if there is a TiVoGenie announcement in the near future.
Having a cloud backup would be a nice feature, and it wouldn't be terribly difficult to implement. DirecTV already knows what shows you have recorded on your DVR, so they easily keep a database of those shows a la NetFlix available in the cloud and download them to your replacement box upon activation, along with your Series Manager subscriptions. This would be a huge value-add.