Cincinnati's streetcar a precursor of gentrification?

Today in my Urban Sustainability class, two gentlemen from the City of Cincinnati gave a presentation promoting plans for the proposed streetcar joining downtown, uptown, and OTR. I was surprised to hear substantial criticism from my classmates and professor, as mass transit is generally considered to be a step in the right direction for sustainability. My professor and teacher's-assistant both raised questions about the streetcar's potential for gentrification.

Without question, the streetcar would promote economic development around proposed rail lines. Should we then oppose the streetcar because it has the potential to raise property value and thus taxes for the lower income people that currently live along proposed lines?

Probably not.

The streetcar is an example of a neighborhood improvement that can raise the quality of life for both inner city residents and the middle-class individuals that may chose to visit or even move to the inner city. Aside from improving mobility, the streetcar could also court beneficial developments such as grocery stores to the inner city. Rather than to oppose the streetcar, it should be promoted, with the provision that safeguards be put in place to protect lower-income groups that live in areas with potential for gentrification.