Disney has very little land at the
Disneyland Resort in California (compared to WDW), so a Disney Vacation Club there would almost have to be a highrise structure. That's much more expensive to build. Presumably, they could "liberate" some of the land now used as surface parking for Downtown Disney or as cast parking, but that would require another costly parking structure. There's also the 50+ acre strawberry field that Disney acquired from the Fujishige family a few years ago, but that land and an adjacent cast lot are slated to be a third theme park.
There's certainly not any announced plan for a
DVC project at the Disneyland Resort, but I suppose there's a small chance that Disney might eventually decide to build an on-site Vacation Club -- especially if they decide the a third theme park is a bad idea.
By the way, I wrote an article. "Disney's Newport Coast Villas, the Disney Vacation Club that Never Happened." See
http://www.yesterland.com/ncv.html