From a sheer demographic standpoint, there will be less taxpayers in the future. The richest generation is retiring, the next generation is not going to be near the same income.
Sure, there will be some STEM jobs, but with manufacturing being done in lower wage countries, there will be lower wages and lower taxes paid.
Robots will be doing a lot of work, bringing in lower page workers to replace higher paid workers will continue. Technology will continue to make many jobs obsolete. Not everyone can be a robot mechanic. We do not need that many, and many people do not have the aptitude necessary.
New college grads cannot get good jobs and they miss some prime years building a career. Most of the population growth is from lower skilled individuals. That is why a fast food server will eventually become a lifetime career, not a stepping stone to the workforce.
In the Baby Boom generation, back in the 60s, there was no such thing as getting paid to do nothing. You worked if you wanted to eat. There was a stigma to getting assistance. In today's world, it's no big deal.
So you have the highest paid people in the USA, paying the most in taxes, retiring. They are replaced by lower skilled and lower paid people.
Do the math. It's probably a exponential equation that tax collections, unless adjusted, will be a smaller and smaller amount than what is needed.