Wait, do you actually think ENT, ophtho, anesthesiologists are coming out making 350-400k in big cities? Starting salaries even for high paying fields are not astronomical. In fact, my ophtho buddies who are looking for jobs right now are getting offers <200k in big cities. The urology residents I know are getting 250-300k in medium to large cities. However, that doesn't mean that their mid-career salaries will remain at those amounts. The cards attendings at my institution who are 7-10 years out of fellowship are pulling 300-350k for general cards and 450k for interventional. I can assure you they didn't start out with those numbers.
But, throwing this money exercise aside, it's entirely false that cardiology is not a competitive subspecialty or that IM is getting less competitive.
And as far as reimbursement cuts for cardiology, just keep in mind that this isn't a problem exclusive to cardiology. Cuts are happening across the board, and will only deepen as we move further into debt. There's really no escaping this problem in any field of medicine, and will ultimately not affect cardiology competitiveness with respect to other specialties.