Lot of years are left for your kidneys to survive. The in drugs will increase the amount of immunosupressant drugs. The change will increase chance of infection slightly. The effect on kidney function is not clearly known. If you have some urine protein excretion, then it may increase a lot with this change. Also check your lipid profile
which is also likely to worsen.
You may be thinking then why your doctor changed the medicines. You should discuss with him. There may be a reason he sees in you that has changed your medications.
Hope it helps.