The 5 year max is why the 10 year handgun license would have to be eliminated in exchange for using the license to replace the NICS. OK2A has advocated bills in the past couple of years to do so along with lowering the cost of the license, but we would have to give up the 10 year license to comply with federal regulations.
Since it was that way when the SDA started back in the 90s, I suppose I could live with that. I sure do like the 10-year term, though. I'd think there would be some other way to satisfy the feds (there's an entirely separate argument since the feds are a creation of the states, not the other way around - tail wagging the dog, if you will) with some level of regular license surveillance.