I have been coaching for a long time and yes, I do think it’s possible but very dependent on the situation.
You would need a lot of talent and natural ability, but, then again to make elite regardless of the age you start you need a lot of talent and natural ability.
What you did before gymnastics will also play a role. Generally the best window for developing flexibility is 6-11 years of age. After puberty muscles become stronger and more solidified to bones and it’s much harder to develop flexibility. But if that flexibility had already been developed, say from dance or something similar it could work.
Toe point is also better developed in your children. The bones in the foot are softer and the point shape can be developed with slow and steady practice. If it’s not there by the time the bones start to really ossify then it may never develop. But it could have been developed already, say through ballet.
It can be easier to develop bigger tumbling skills when you are small, your centre of gravity is lower, you dont need as much strength and power to get your body around, you are easier to spot etc
Time is also a factor, it takes many hours in the gym to develop elite skills. When you have had less years in the gym, and are busy with high school life and beyond it’s harder.
Plus few coaches will take you.
But having said that I have seen it happen. Started gymnastics at 10, trained recreationally once a week until age 12. At age 12 took it seriously and was Elite in a few years. By 15 was ready to compete Senior International. But that is in Australia and the standard is not as high as the US.
Also the ages of 11-15 are very fragile for many girls, rapid growth and change can make them very prone to injury. Throwing them into elite gymnastics training without years or training behind them probably isn’t the greatest thing to do to their body.
But it is also my belief that you can take up gymnastics as an adult and make elite if you have the right body type, the time to train and you have had a chance to develop the crucial body preparations through other activities when you are younger.