While this is interesting, I don't think it will make much of a difference clinically.
The reason is that cerebrospinal fluid (CSF) circulation and drainage is something that doctors, especially neurologists and neurosurgeons, are very keenly aware of, and we have ways of treating issues where the CSF is not being absorbed.
As the article mentions, you produce around 500ml of CSF daily. If you do not drain the CSF, you will die fairly quickly as the pressure inside your head builds up. This can happen due to a tumor or from blood, and when this happens it is an emergency.
The emergency treatment consists of drilling a small hole in the skull, and putting a small tube into the fluid filled space of the brain called a ventricle which allows the fluid to drain. This is called an external ventricular drain (EVD). You can do it at bedside with an awake patient, lidocaine, and a hand powered drill. I have probably placed dozens if not hundreds of EVDs.
Many times the blockage will clear with time (for example the blood reabsorbs) or with treatment (you take out the tumor or drain the blood clot) and then you can remove the drain. Other times, the patient will need it long term. You then place what is called a ventriculoperitonal shunt (VP Shunt). There the tube still goes into the brain, but instead of it coming out, it is tunneled under the skin to the abdomen, and the fluid is allowed to drain into the abdomen. Everything is under the skin, so the patient can go about their normal life.
This inability to drain, can also be less dramatic. There is a condition called "Normal Pressure Hydrocephalus" which happens gradually. You often see it in older adults, and it can present as mental slowing. If a CT Scan and MRI of the brain show evidence of this, without any signs of tumor or blood, you can do what is called a therapeutic lumbar puncture (spinal tap). What you do is you insert a large needle into the fluid around the base of the spinal cord, and measure the pressure and drain some of the fluid. Then you let the patient go home and see how they do. If they improve, then you can place a VP Shunt (as described above) so that the fluid is continuously draining instead of requiring them to come in and have a spinal tap all the time.
So, while the circulation and absorption of cerebrospinal fluid is very important, I am not sure how much these lymphatics translate from mice to humans, and it is not like doctors are not aware of and don't have treatments for too much cerebrospinal fluid. If progression in Alzheimer's disease was just a matter of draining cerebrospinal fluid, we can already do that today.
Source: I was a neurosurgery resident.