I have an old asphalt driveway beyond repair- it's there a product/process to overlay concrete on it without digging it all up?

You Be Just Masking The Problem, And Next Year You'd Be Asking Is There A Way To Overlay Asphalt Over Concrete,
Concrete Need To 4" Thick To Support The Load Of Your Car. I Wouldn't Thick You Can Go That High And Not Have Issues, If It Is Really Unrepairable Then You Need To Consider Just Replacing The Drive Way, Ashphalt Is Cheaper Than Concrete But It Want Last As Long, You Have The Way The + And - Of Both.
As Far As Digging It Up, For A Concrete Company That Pours Driveways, Its Not A Big Deal For Them,

Normally you can merely re-cap the asphalt with asphalt. But only a professional who can phsycially look at it will know.