A hybrid agile/waterfall organization should NOT be your goal.
An agile/waterfall hybrid is a temporary state that exists during transformations. It‘s not the state you‘re aiming for.
Agility and waterfall come with different values and beliefs. You cannot simply switch your values and beliefs multiple times a week!
An agile/waterfall hybrid always causes friction at the interface. That‘s an inefficiency and pain we‘re willing to endure during a transformation. But this pain is not something we want forever.
So before your embark on an agile transformation, ask yourself which values and beliefs you want represented in your corporate culture. Then go for one or the other. But please don‘t make people change their values and beliefs from one department to the other.