Such articles perpetrate the myth that developers die after X. It's obvious that the majority of devs will sit in the 20-30 bracket just due to popularity and increased opportunity over time. Industry is growing and the only way to get new people in is to train young people.

Stop asking yourself this stupid question. Only bad developer careers die at 35. If you're good and keep developing your skills, you enter the gray-beard mode right around 35-40. We have our share of 40+ engineers and we've just hired a 50+. We also hire 20 somethings, and they are great, but totally different.

I laugh at the idea of a 24 year old senior engineer. Unless you've been hacking from 10, there is no way you've seen enough shit to prevent shit from happening. The really senior engineers really know their shit and are less prone to making wrong choices.

The only challenge you have with 40+ is culture fit. You can mold young engineers according to your culture, while 40+ is take it as it is.

So we search for 20+ that are open minded and are willing to grow and we're looking for 40+ that have not stopped growing and will fit in our culture. I've seen people at 60+ that can replace full teams of people in terms of quality and quantity of output.

The "age" problem exists only in your head.