Question: Is Medicare going to be significantly impacted either care wise or cost wise? More specifically is this, will the Supplements be really expensive to cover the shortfalls?
Who really knows? However, for budget purposes, the reform bills are counting on $500 billion in Medicare savings over the next 10 years. The fact that the current bills count on Medicare, the biggest unfunded liability in the country, to help fund 50% of healthcare reform doesn't pass the "smell test" with me. IMO, the sensible thing to do would be use any Medicare savings which actually materialize to shore up Medicare.
With reguard to your specific question, seniors are a large and fast-growing voting block, so it's hard to see politically how any significant Medicare cuts will actually occur. As an example, one of the places where the President and Congress is looking for large Medicare savings are the Medicare Advantage programs, but the Senate has already grandfathered those currently in existence to secure the vote of Florida Senator Bill Nelson in its quest to reach the "magic number" of 60 votes.
With regard to the Supplements, I would expect their premiums to grow in line with Medicare expenditures/enrollee. Remember, the Supplements only cover Medicare-approved procedures. So if Medicare were to stop approving certain procedures, the Supplements would no longer cover them. On the other hand, if Medicare raises deductibles or copays, these may be picked up by the specific supplemental policy you have, and, thus, would add to their costs. For example, if Medicare raised the part B deductible (currently $155) to $1000, any supplemental policy which paid this deductible would likely pass along this increase in its premium.