It already does. The FMC gives you an optimum cruise altitude and guidance altitudes for heavy turbulence are generally 4000 feet or more below that optimim.
If such information is already present, then I am happy
But we will get back to it.
What you are proposing is starting to sound more like a technical impossibility: a device that takes radar returns, calculates the intensity of the turbulence in a rapidly changing weather environment then fires off a series of predictions of what your margins will be.
It is a bit different. Why? Because you don't need to say: how to fly in an environment where you shouldn't fly. All you need is to evaluate risks, considering your speed, altitude, weather, and any failed instruments (and conditions for icing)
When you determine how safe "your future" is, you use a simple scale.Say: 0 is totally safe, 1 is certain disaster.
If without pilot intervention the situation becomes risky enough in some time frame, you get an advisory. To buy you some time. If you see the computer predicts a probable / possible threat to your safety
before it happens, and
before you could detect it without this system in essence buys you time, where you can react.
Notwithstanding the technical difficulties, you don't need a computer to tell you what speed to fly at in turbulence because the manufacturers have already told you what speed is best.
I know about turbulence penetration speed.
You don't need an amber advisory because you can see what speed you're doing on yout instruments and compare it to the manufacturers published turbulence speed. If you need a flashy advisory to remind you of your turbulence speed you shouldn't be in the flight deck.
What you say is about
the present, the nature of early warnings is
they predict a probable future. You speak about how hard it is to analyze the data, and it is
indeed a huge task even more for a human being in the flight deck.
But computers are efficient at analyzing huge amount of data, quickly and efficiently. They won't give you a strategy about "how to avoid the worst of the storm", but will be able to tell you "how bad it will be if we are going this way".
The computer can tell you, where can you end up, with about what possible airspeeds with sane and safe maneuvers, and if it would get you into trouble, in some timeframe it could warn you.
The goal isn't to "tell the pilot how to fly", the computer shouldn't know that, this is why we have a pilot there. But it is to give more time for a pilot to react to a
predictable threat.
Imagine why TCAS and GPWS prevents accidents. They don't report the collision, but detect a possible threat that is predictable with some certainity, and give you time to safely avoid accidents. TCAS doesn't determine "how close you would be to a collision" without it, it isn't super precise.
Even if such a device existed, there are up and down draughts throughout cells with different turbulence associated with each. Each encounter will be different and poses the potential to see you chasing one speed target only to find it's a completely different one 5 seconds later. You'd be more likely to get into a pilot induced oscillation from following that, which will do you more harm than good.
It wouldn't give you speed target, it would give you a warning that tells you: if you don't act soon, in some time you will end up flying into a thunderstorm and some turbulence, and you won't be at safe speed / altitude for that with safe maneuvers.
And the pilot makes a decision based on it.
The computer shouldn't tell you what you do, since you should make decision. But should give you feedback about how safe / unsafe some course of action can be.
A speed target
inside the turbulence isn't an early warning, it doesn't offer you a chance to have the best possible speed and altitude.