Cuban-
Just to clear up one thing-
In the real world, most carriers fly a constant Mach cruise schedule. For any given indicated M (.82 or .84 for example), your TAS will actually DECREASE as you climb.
TAS is dependent upon temperature, not altitude. So when you climb, the OAT is colder, so for any given indicated Mach, the TAS is lower. For example, TAS at FL 370 is about 20 kts. slower than at FL 270 at the same indicated M.