Thanks to MikeH - already have a replacement on the way.
FYI, here is what was happening - the 722 started freezing last night while watching either recordings or live tv. Not the type of thing where it rebooted but a hard lockup. Reset several times (unplug method) and it degraded to the point I was getting the hard drive has failed error message. It lets me watch live tv but no dvr functions - says to wait 5 minutes and try again or reset again - always get the HD failed message though. I left it unplugged over night but got the same thing this morning. I hoped I could get it to limp along until I could dump some recordings to an external drive, but that's not looking good (goodbye latest GoT season, etc.).
Anytime one sees hard drive related issues, I'd say the odds of it not surviving or failing soon are about 90%. Unless you have a lot of things recorded, no backup, and don't want to lose them, the easiest thing is to just replace the receiver. A few people get an error like this and rebooting takes care of it and they don't have any trouble later.
Interestingly the old DVR did start working again after I left it on for a day and then reset it. It allowed me to back up some things I didn't want to lose, but I will replace it anyway as, like you said, chances are the drive is going to fail for good.