Maybe there will be a "Hopper 3/2" where they limit the number of tuners to eight, allowing two such DVRs to be added to an account, but I would think the best thing about the Hopper 3 is the elimination of programming two Hoppers to coordinate recordings between them and the Joeys. Much simpler to have only one Mother Hopper talking its Joeys.
And why the Hopper didn't have this feature out of the gate? Well, this sounds like some pretty slick technology, pulling the requested transponders out of the six possible satellite streams (WA, three positions, Even/Odd) and putting them together to feed back over the one 3 GHz RG6. Possible and feasible now; perhaps possible years ago, but too expensive and therefore, not feasible.
Now, to having separate Recordings for "Adult" and "Child" Joeys: That sounds like a great idea, somewhat akin to Microsoft's "ABE" (Access-based Enablement) where files are invisible if you don't have minimum access rights to the file. You look at your recordings from the "Adult" Joey and you can see all the TV-MA and R material. Your children use their Joey and all they see is the G and TV-6 programs. That would be nice.