Actually, Dr. Komaroff, does not say that there won't be a cure in 20 years. He says that they don't know enough yet to make an estimate. In addition to diagnostic tests, he says that he's optimistic that there will be treatments that definitely improve symptoms within 20 years. In this context, "twenty years" is more like the outside range as opposed to an estimate of how long it will take.
Things could happen much more quickly if a potentially "curable" cause is discovered. This is the kind of discovery we may be seeing with autoimmunity and Rituximab. There are other potentially "curable" sources of the illness as well, such as an altered microbiome that promotes some kind of chronic immune activity. Finding something like this would be akin to the kind of "home run" that Barry Marshal and Robin Warren hit when they linked h. pylori to peptic ulcers. It's rare, but it does happen.
Also, I would not discount the value of developing treatments while searching for a cure. There are many diseases that they've been working on for more than twenty years and that they have literally spent billions on which still have no "cure." Still, treatments have been developed that can manage some of those illnesses. HIV infection is one obvious example. Likewise, there are several treatments for relapsing-remitting MS, but still no outright cure.