The ideal situation here would be to hop onto a train or bus, near my home, and after arriving near my destination be able to walk safely the rest of the way. Now, unless I worked in Benton County and lived in Fayetteville, riding a light rail train wouldn't have much of an appeal for me. I enjoy going up to Rogers occasionally to shop or dine, but it just doesn't have the amenities to support mass ridership on light rail. The same could be said about Fayetteville. Hopefully I'm wrong, but it seems like other than business travel light rail in the NWA corridor would be sparsely used.
The reason that mass transit systems work so well in large urban centers is because traffic and finding sufficient parking is a tremendous inconvenience and expense. Also, and this is really key, pedestrians have easy access to wherever they need to go. Fayetteville and Rogers have all the same basic amenities and are extremely difficult to get around on foot.
Will a centralized, light rail system encourage infill and more dense urban living? It seems like it would, but to what extent? Also, would that growth be enough to attract the necessary amenities to create enough daily ridership to justify a light rail? It seems like the more natural course would be letting population growth determine mass transit development. Certainly, it's necessary to plan ahead and have the infrastructure in place for mass transit development and also key to NWA's future growth is focusing on developing pedestrian friendly urban cores to link through mass transit systems.