@Dontgiveup The simple answer is YES. The expectation is that normal drainage through the Jugular Vein will be restored and collaterally won’t have to reroute blood as much and will shrink back to their normal size. So it is clear that the volume of blood that Jugular Vein drains is much bigger than what the Collaterals are designed to drain so while they can help, they can get overwhelmed when the IJVs are impaired as result, they can compromise blood flow to the spinal cord or can compress it so returning blood flow to IJV will definitely take the pressure off of them.
Here is my 3D rendered CT Scan of the Neck. You can see the “Blue Arrow” that is pointing to dilated collateral Vein on the left side where the compression to my left IJV is extreme. I expect it to shrink back to normal size after it is removed.
Remember that Higgins & Axon study, if you look at the axial images of the patient, you can see that collaterals are dilated/thicker before surgery (A) and the collaterals shrunk to a normal size after the first surgery (B) and went back almost to a normal level after the second surgery (C).
Source : Dr. Higgins & Dr. Axon : Spontaneous Intracranial Hypotension Complicated by Subdural Effusions Treated by Surgical Relief of Cranial Venous Outflow Obstruction