This is a fascinating article about the history of software development. For me the key quotes are:
The thing that killed Waterfall was that discovering your spec was wrong months later, after lots of code had been written - and fixing it cost a fortune because writing code was the most expensive part of the process.
The key reason Agile was invented was to account for the high cost of writing code, so yes, that part of the Agile value proposition is no more.
The risk isn’t that AI development is inherently Waterfall. The risk is that organizations with latent Waterfall instincts will use spec-generation as license to do the bad thing they always wanted to do — front-load requirements, skip customer validation, equate a fancier document with a better outcome, and ship one massive thing every quarter.
My understanding is that Kanban came from Toyota, which is an agile way of working.