Take your time baker all is good.
I suspect Schulte would be the means to introduce evidence against various individuals such as Brennan rather than through Assange.
That would of meant JA had to agree not to continue publishing his Vault 7 & Vault 8, thus a deal has been made/agreed to? in order to get the information into the Courts legally, Assange free from charges, while still getting legit info to the people.
My 2 Cents.
They would have the forensic trail according to all the information that has been stated per Schulte himself.
They would not need Assange testimony.
They have come to an agreement whatever that agreement may be, but they would not require Assange testimony considering the complete trail it appears Schulte left.
JA is not in the Embassy.
No. There are others ways of proving things without compromising WL.