At some point the saturation for (entry-level) programmers with degrees will be enough that (entry-level) programmers who are self-taught will be in zero demand.
This assumes that a) the number of CS graduates keeps growing at a steady rate, and b) that the market puts a significant amount of value on a degree. Personally, I don't think either of those is true, especially the latter. With the cost of education continuing to rise in the US, I actually believe the value of a CS degree is trending towards zero, considering that the cost of the alternatives (code school and self-teaching) is much lower in terms of both money and time. And anecdotally, I've noticed that software engineers are in such demand right now that even companies that officially require a CS degree are easing that requirement, opting to instead focus on the potential of the candidates at face value.
Doubtful, you're ignoring the fact that self-taught (entry-level) programmers cannot simply be replaced by (entry-level) programmers with degrees (or vice versa).
Both have their up- and downsides, and treating them like equals is ignoring that which makes them each of them unique.
There will always be a market for self-taughts, if you don't understand this, you don't understand what makes a self-taught special.
As an employer, I want the best. All other things held equal, someone trained from some kind of institution will give me more confidence for employment than someone self-taught. Self-taught shows initiative, but institutional learning applies a baseline training employers can trust.