Perhaps time will prove you right, though (in the nicest possible way!) I hope you’re wrong.
Personally, I’m optimistic that we can do much better than 2x on the important metrics as mainstream programming languages and the programmers using them adopt ideas that already exist in more obscure languages, programming research, and development teams that don’t necessarily publish their experiences openly.
I think some of the potential gains come just from making it easier and therefore quicker to read and write our own code. Better syntax, more expressive language features, a more comprehensive standard library, and eliminating some of the historical baggage like how null/undefined are handled could all help a lot compared to today’s TypeScript, IMHO.
There are also other areas, such as safety and making it easier to work with other code from within or outside our own organisations, where today a huge proportion of a typical TypeScript developer’s time is probably wasted on things like wrangling dependency trees that could be much smaller and better managed, investigating preventable defects that currently reach later stages in the development process before they are noticed, and writing unit tests for negative cases that would be unnecessary if the language itself designed out those possibilities.
Something that struck me a little while back is just how unimaginably large this part of the programming industry has become. We’re talking about millions of developers working on web applications and companies collectively worth trillions of dollars. How much would even a 10% long-term improvement in developer productivity be worth to the world? What about 200%? What about 1000% or more? Personally, I think we still have a long way to go before we run into any inherent limits on developer productivity, and we’re learning more all the time.