I have some historical comments on the grades between MS60 and MS70. About 30 years ago, almost all uncirculated coins were described by collectors and professionals as MS60, MS63, and MS65. Even though the Sheldon grading scale theoretically included 70 points, not all 70 points were used. This is still presently true in grades 1-58. There are not 10 AU grades that can be provided. There are only 4 AU grades: 50, 53, 55, and 58.
In theory, PCGS or NGC could decide to start using 51, 52, 54, 56, 57, and 59. If they chose to do this, then there are coins that were "truly" 54 that may be in an AU53 or 55 holder from the past. If they were regraded they would go from 53 to 54. If that happened, would you say that there is gradeflation? The grading company would say, "No, we have only improved the accuracy and resolution of our measurement system by increasing the number of options". There would be many many collectors upset by this kind of change because their 55 graded coins would become 54.
Something similar to what I described happened in the 1990s, and is still happening in the United States. There were many PCGS / NGC coins that graded MS65 that would now grade MS66 or MS67. At the time they were graded, MS65 was used heavily for very high quality uncirculated coins, and MS66 and MS67 were not used. Even when the MS64 grade was introduced, it took graders some time to establish a standard of what an MS64 looks like. It took time before MS64 started appearing as often as it should.
I only started collecting 10 years ago, so most of this saga is ancient history for me. It is still a common topic of discussion with high-end coins and it is periodically written about.