In 2012, it's 8 TeV by the way. Hopefully 14 TeV in 2014.
It's a little more complicated than looking at the total center-of-mass energy and saying we can discovery any particle up to the max. A single proton is made of multiple constituents, and a proton incoming with 3.5 TeV (or 4 or 7) of energy represents the total energy of that system. When two protons interact, it's actually two constituents which are interacting, and they will have some fraction of the proton's energy. So typically the probability of producing particles drops considerably as you look for more massive particles.
That said, the central sentiment of your message is correct. There is a lot of potential signals that remain to be investigated. There could even be particles found with considerably less mass than the Higgs, but which have an unusual decay signature which we haven't been sensitive to yet.