This is less than a 10% loss. Are you really thinking this is excessive, or just being wishful?
It was my understanding that Tesla expected a <30% loss in 8 years. That's the replacement point, where a battery has lost 30% of its charge.
My car was guaranteed for 8 years unlimited mileage, so I am planning on having less than 200 miles of range at that time, or a loss of about 80 miles. The degradation curve is tested to be a larger ramp down in the first few years, and then leveling off for the rest. 20 miles loss at 75,000 sounds pretty good, unless you think somehow that the battery will not degrade. But I suppose there are a lot of people who think that it should be like new in 8 years. Human nature.
My car has about 43,000 mi on it in a year and a half, and I am at about 3% degradation: that's about 6 miles lost. Hopefully in another 6 years or so, we will have lots more superchargers, or availability of bigger and stronger batteries.