Early this week, The State Journal-Register (the newspaper of Springfield, IL) reported that the Abraham Lincoln Home National Historic Site is almost finished developing a new "General Management Plan" to guide the park for the next 15-20 years. The process, undergone by all of the National Park Service sites from time to time, envisions the visitor experience to the site in the future.
This planning process started in 2005. The National Park Service is considering four options to further develop the site, including doing almost nothing at all or further developing the lots surrounding the Lincoln house.
The various plans, as they stood in 2006, are available in this .pdf document. None of them seem to propose changes to the Lincoln home itself. Instead, they focus on possible changes to the neighborhood around the house (which is part of the National Historic Site). There also are some mundane proposals, like the addition of some restrooms or moving the tour bus pick-up location.
One of the intriguing proposals is to show where some of the other houses and outbuildings (barns, carriage houses, and privies) existed in the neighborhood while the Lincoln family lived there, not by building them, but by building steel frames of them. (Evidently, this has been done in Philadelphia to show where Benjamin Franklin lived. Of course, it would be more expensive to build a 3-story brick colonial house in Philadelphia than a wood frame house in Springfield, so one wonders why you wouldn't just build the house exterior.)
The neighborhood is the most underused part of the Lincoln home site, even though there are displays in two of the houses (and offices in others). Some interpretive signs talking about the neighborhood and the Lincolns' neighbors would be an excellent addition to the site, regardless of whether they construct buildings, frames, or foundations on the lots. I realized this potential while on a tour of the house with a guide whose tour focused on the Lincoln family as one family in the neighborhood. [Sidenote: the best part of touring the Lincoln home is the freedom that the rangers have to shape their own tours. I've been through the house a half dozen times or so, and the tours have all been very different and very good.]
While any changes may take years to complete, the general plans should be decided in the near future. It will be interesting to see what they decide.