Are there more collectors who are interested in a given Vintage Collection figure sourced from The Clone Wars than are interested in any given Original Trilogy figure? Maybe, but that is not, nor is it ever, the question. It's not about how many individual customers will buy a given figure. It's about how many of that figure will sell. The latter provides a massive cushion for sale success. So let's count how many Episode IV Luke Skywalker figures your average hardcore (oxymoron) collectors
will buy.
OT diehards like to set up dioramas of the iconic scenes. Each of those dioramas will require its own set of figures. So how many Episode IV "Farmboy" Luke figures would a serious OT collector needs for their displays:
1. Lars Homestead
2. Purchase of the Droids
3. Landspeeder / Tusken Attack
4. Ben's Hut
5. Cantina
6. Big Millennium Falcon
Thasalotta Lukes, and I'm not even counting simply retools such as the "Death Star Escape" Luke. In the military, they talk about technology that serves as a force multiplier. When you have an OT based figure that is represented in multiple scenes, it serves as a customer multiplier. Even if there are half as many hardcore OT collectors as there are collectors of newer media, that would still potentially translate to twice as many figure sales.
As I often say, there are not many investments on which I would risk the future longevity of the Vintage Collection. A newly tooled Episode IV "Farmboy" Luke is one of those things. It's money in the bank. I would bet my obsessive hobby on it. I would personally buy two solid cases if it's ever announced.