Kudos to Chimbu and VirginExcess - they have nailed it.
The reality is that the problem is commercial problem as much as a technical problem. Automation has been a commercial necessity in the IT and Utility (Power, gas, electricity) industries for decadeds. It is now a commercial necessity in aviation. The way forward is to accept the fact that pilots are now dependent on automation as their employers can no longer afford to keep the hand flying skills current.
As such, any reduction in automation due to unreliable airspeed or any other criterion should have a mandated gradual reduction in automation based on the computer's best estimates from the remaining reliable telemetry. What is no longer acceptable is the sudden "I give up" programming to hand over full manual control to pilots in an instant, as what happened with AF447.
It is no longer economical to train pilots to hand fly in such situations - the automation response must be gradual and very unabiguous to enable pilots to adjust to a fully automatic to semi-automatic flying mode. Just giving up and expecting hand flying skills is no longer on the cards.