If enough funds are appropriated into a light rail system the system would flourish over time, though yes it might encounter some difficulties until the city reaches its full potential. If you figure the best corridor for light rail to be the neck area from North Charleston down to Charleston there's massive potential for that area to grow--and the light rail will help it get there.
International Blvd. development is reaching south towards Magnolia which is in close proximity to park circle and noisette. Still moving south you'll hit the upper king revitilization, and some small towers going up near the bridge (an area I like to call Underbridge-- there are a few towers that are going up over there that will have beautiful views of the harbor and bridge and if there's a light rail connection reaching further into the dowtown destination there's no telling how this area can grow). This is also an area the the Ginn company has been interested in developing in once the market turns around.
Moving downtown the system should end right behind King street behind the College of Charleston Simons center where there's currently a HUGE parking lot which would act as a fantastic end point for a light rail system. The parking lot is right behind King street's major shopping corridor and has the college and a plethora of businesses to draw ridership from.
There are two points to make about light rail in Charleston: The various developments along the neck into downtown are great for the community and if a light rail system is put in place the holes between these developments will fill in over time. Secondly the construction of a light rail system will take a very long time before it is ready--especially here in Charleston where people love to talk about things until the project passes from their minds entirely. In the time it takes to build the system more and more developement will occur until it's ready. While planning and construction are going on, developers will get a cue on where the corridor will run and where to develop. Chareleston is ripe for light rail, it's just a question of whether we'll take the initiative or not and when we do it execute it correctly and devote enough funds into a very expensive project.