Let's be real here. While this will likely increase FSD adoption, the real reason it hasn't already increased is not only because of the cost, but also public perception.
Just go on YouTube and look through any comment section, or any social media post about FSD. You will quickly find out why a lot of people are hesitant to not only purchase or subscribe to it, but even try it. People simply aren't willing to be what are essentially beta testers. And I can't say I disagree with them, FSD up till recently, and even now in some rare instances can be hit or miss. Not to mention the current hardware limitations. I, too, would be very upset if I purchased a car under the impression that it would be able to drive itself. Only to be told years later that is not the case after spending $8,000, or even paying a subscription for months and years.
Even now, as a current Model 3 owner with HW4, I am being told that my hardware will soon be outdated. Even if my car will be capable of some form of full autonomy, it is not reassuring that there will be a point where I will stop receiving updates to add features, make it safer, or just generally be better. Especially since there is currently no upgrade path.
I believe they have to address these other things first, or at least in tandem with cost, before they see any significant increases in adoption.