Let me explain this to you. You are trying to do what pretty much every other neph grad is thinking, which is how to get out of general
nephrology because starting salaries are low. Everyone is thinking the same thing as you are. Trust me.
1) In regards to CCM, there are only limited number of 1 yr CCM fellowship programs, so it's far from certain that you will get it. One place I know had
50 nephrologist applying for 1 spot that year! Best of luck, but no guarantees you can get it.
2) In regards to IN, you can get trained, but you will not make more money than a general nephrologist in your group. You need a large dialysis population to feed you the fistulograms/declots, so it's not like you can open your own access center and expect referrals. Large nephrology groups start access centers as an investment. They often will train new recruits and get them to work in the access center. The physician compensation for these procedures is small. The majority of the revenue come from facility fees payed by medicare/insurance which is split between the partners. There's a reason why these older guys are asking you to do them! You may not know this, but you are actually 5 yrs late. Medicare reimbursement for these procedures has dropped 40% in the last 5 years! Many access centers are struggling to survive!
It will take you years down the road for you to appreciate what I said today. So all in all, good thoughts, but it may all come to nothing.