It's possible, but there's no need to guess about such a major job. Doing compression and leakdown tests would indicate if the engine is mechanically sound or not.He also thinks it might be time for an engine replacement
It's possible that the rings have seized on one or more cylinders. In that state, they would no longer seal against the cylinder wall. VCM has been known to cause this issue. It would also explain the high oil consumption. Again, testing the engine would confirm or deny that this is the problem.
As discussed above, your cats are probably blocked. That would explain the engine's inability to rev past 1500 RPM. However, before replacing those expensive items, you have to address the oil/engine problem. Otherwise, the new cats would quickly suffer the same fate as the present ones.