There certainly will be people willing to pay to get out of the traffic - but will there be enough people to do that, for this company to get anything close to a reasonable return on investment? I just can't see how - unless the state removes the freeway option for the same route ($7.2 Billion is LOT of money).
I certainly wouldn't invest any of my money in such a project. Most of the tollways around urban areas such as Dallas, Houston and Atlanta seem to make more sense economically (although the Hardy toll road would make more sense if it actually went anywhere).
Are you saying that they plan to eventually remove I 35?