This is exactly how it will work across the board (not just call forwarding and speed dial). We are currently building new changes to call forwarding that will replace the existing one.
These changes incorporate what you suggest and also factor in other things like time of day etc. i.e. between 9:00pm-6:00am forward to voicmail (as you are asleep right

)
It is probably worth noting that these new features will only be made available to "premium" members.
More announcements on VoXaLot premium will come soon......