I love the "points of light" concept as the implied setting for the core books, but I am a bit distressed at the idea (and the support for it) that all campaign settings be built around the concept. I'm torn on the issue a bit.
I think 3rd party publishers will definately put out points of light for 4E. Freeport and Bluffside were ahead of their time, and the exampled to which many points of light will have to live up to. I'm personally working on one that I'd love to release online, along with a series of companion adventures, if I can wrap my head around the business side of it all... so I suppose I am banking on gamers just like you that will be looking for easily dropped in campaign elements. But...
I think overuse of the concept in established campaign worlds can kill the unique flavor of those worlds, and the line between some of them is already thin enough. A drop-in here or there will be fine, but if whole worlds are made modular, the distinctive qualities that have give them each a fan base will dissolve.
If this is how it goes down, I suspect in 18 months or so you would see some radically different settings coming out of the 3rd party publishers with radically different elements that make them more distinctive, and less susceptible to being broken up and tossed into other settings.
All of this is imho of course.
I prefer campaign setting guides to be the primary resource for the entire campaign setting. I want as few supplements as are necessary, as I want my setting guide to cover the whole setting in broad strokes and then drill down to cover points of interest in additional detail.