The 4680 cell easily bests a million miles with less than 10% degradation. It's rolling out in select new Teslas now. 5000 cycles at 300 miles each is a very low estimate.
Tesla started keeping it under wraps as soon as the Osborne Effect was clear. The million mile battery could've bankrupted Tesla if they announced it and confirmed it.
The Osborne computer company went bankrupt by announcing its next generation tech too soon, leading consumers to stop buying the first, and it cut off the lifeblood of cash as customers waited for the new, much better version.
en.m.wikipedia.org
Independent researchers stopped publishing tests on it. Tesla stopped making videos about it. New warranties don't increase in mileage much. But those are 2 to 4 million mile batteries. As soon as they say so, they will stop selling current cars.
Tesla paid people to shut up about it. The Osborne effect is an existential threat for companies that innovate too fast.