I'd be curious if the number of full-time paid actors as a percentage of the total population has changed since Classical times. I wouldn't be surprised if it hasn't. (No data. I can't tell either way.)
Medicine has indeed changed. But plenty of other occupations - manual farming, blacksmithing, even full-time life in a religious communities - have all-but disappeared. (That latter "occupation" holding a very non-trivial percentage of the population for at least a thousand years.)
Jobs exist when there's a perceived market for their output. No one is going to argue that today's software dev practices can't be improved and streamlined with AI, or even with dumb automation.
So the lower tier of IT jobs will indeed go. And it will not be replaced by new jobs for those with an equivalent (low) level of talent.
There's actually something like Maslow's Hierarchy of desirable outputs from jobs. On the lowest tier you have dumb musicle, which is easily automated with animal help and then by machine aid. At the top you (probably) have political leadership - not because it's necessarily genuinely productive, but because it's good at making itself appear critically important. Between those extremes you have various layers that rely on different blends of muscle, IQ, original creativity, ability to command resources, people skills, strategic political skills, and persuasive abilities. (...Not an exhaustive list.)
Mechanisation starts low and moves high. Muscle is easier to mechanise than IQ, but a lot of "high IQ" work is repetitive, and easier to mechanise than work that requires strategic political skills and persuasive ability.
Bottom line: it's all vulnerable. No one's job is irreplaceable. Not even the privileged "jobs" at the top of the hierarchy, which are really just pure resource accumulation.