TT and freefile have been around a good long time, yet the percentage of taxpayers using paid professionals has hovered just under 60% for years. Perhaps young tech-savy people will never use us so they won't replace the older and middle-age clients who would never touch their own returns. I actually had a couple of young guys who chose to do their own partnership return after the first year to save money. (As a professional, I didn't touch a partnership return until I had 10 years of experience under my belt and a zillion courses on the topic.) They have no fear of technology until the audit letter arrives. After another year or so under TCJA, I do foresee more clients who no longer come close to itemizing drifting away too.
That said, the tax rules have gotten insanely complex, especially for the self-employed, and lately they change on a weekly basis. How many Uber drivers even know what QBIA is? Heck, people can't even do their own W4s without professional help anymore. (For the first time ever, we are going to start charging for the new version.) And more and more people are willing to pay for things they can do themselves like car washes, lawn care, food delivery instead of driving to the grocery or McD's to get it yourself. So I don't see all doom and gloom but think we'll have to wait to see how it plays out.
Disclaimer: Most of our clients are like Edsel's with complex investments, businesses, trusts, etc. If we had more of an early-season crowd I'm sure I'd think differently about the future.