Just for grins, let's compare the existing 722k with the new Hopper/Joey combination
722k
2 satellite tuners
optional 2 OTA tuners
TV1 output in HD
TV2 output in SD only
no TV3, 4, etc.
no ability to share contents between multiple units
PIP (not sure about TV2, but would be in SD if supported)
Hopper/Joey
3 satellite tuners
OTA possibly available unknown date after launch
TV1 HD
TV2 HD
TV3 HD
TV4 HD
with second Hopper, you get TV5-TV8 in HD, plus the ability to share recordings between all units
PIP on Hopper units only
So to recap, as an integrated system the Hopper/Joey combo gives support for more satellite tuners (with 2 Hoppers you get 6 tuners that can be used simultaneously, vs only 2), more discrete TVs supported (up to 8 in HD, compared with 1 HD and 1 SD), all with the ability to use any tuner or watch any recorded program. The negatives are that PIP is limited to Hopper-connected TVs, and OTA is promised but not delivered.
Clearly, this will not satisfy everybody, but what does? My guess is that most families will be satisfied with one Hopper and one or more Joeys, but if 3 tuners aren't enough, you can add 3 more with another Hopper that integrates with the existing system. I have never been willing to pay for a second 722 to support my second HD TV because then you're locked into watching a recorded program on a particular set; for me that has been a deal-breaker. Having the base unit support 5 or more tuners is overkill for the average family, and would cost Dish more to deploy; the new solution gives the best of both worlds.
If you need PIP on TV2 you can get a second Hopper, I guess, or stay with one or more 722s. Obviously, if OTA is important, you won't be an early adopter of the Hopper. But what else am I missing? Seriously, folks, this is a significant upgrade in every respect, and is very competitive with other vendors' solutions