Yeah, it's terminal. Hoof will drop off, they can't put weight on it, if they do it remains raw. They gradually just move to edge of their feeding area and stay there about a 2 acre area (from what I've seen). Hoof rot isn't the ultimate killer, but its the start of it. Once the hoof falls off and they have a raw nub, they are susceptible to a host of other bacteria. They usually end up extremely skinny, where they are susceptible to exposure (body can't keep warm in winter especially in the rain). At some point they are weak enough they can't stand, and they usually just lay in an area until they die. I came across a bull 2 years ago, that couldn't stand. It was in rough shape, sunken eyes, feverish, I'm pretty sure it couldn't get to water (little over 100 yards away). The smell was pretty overpowering, coyotes had been trying to get him.
From the smell I figured I'd find a dead elk, and I shot a coyote while I was following the scent from down wind within 40 or so yards from him. I found him a few minutes later. He had hoof rot on one hind leg and one front leg. Not a pretty way to go.
I think from the onset of hoof rot, they can usually make it through 2 to 3 years before they succumb. The first year they have a slight limp, no other sign of illness. The 2nd year you see the ones that are starting to look rough, can't put weight on their leg, usually funky shaped antlers if it's a bull (opposite side from the hoof rot side), they can still travel pretty well, but they are 3 legged (like the one in the cam). The last year (3rd or so of hoof rot) is as described above first paragraph.