Oh I don't know about that, I can only comment on my own experiences. I don't have sufficient breadth of experience to be able to say how much of this would be applicable to other developers in other subfields. I do however, like you, look forward to multi modal capabilities. I fully expect it to be able to take a Balsamiq mockup and generate the code to set up the UI for that mockup, with handlers for widget events and all. I've already had it generate UI's from text descriptions, which was cumbersome (relatively speaking - hedonistic adaptation strikes hard here).

Wrt to productivity - I do think it's misleading to look at it like 'it used to take me 5 hours, now only 1, so that's 5x' or some other (imo naive) quantification. It's much more about removing drudgery and thus freeing up mental resources for interesting things. Say I do a task with a certain tool in the same time it took me without it, but in a much less mentally taxing way (because that's what drudgery does to me - activate bore-out mode). From the naive metric pov there is no productivity improvement. But if that leaves me capable of doing more in the rest of the day/week because I don't have to fight myself to move on with something, I'd argue it's still a productivity gain.

Does typing with a nice keyboard and in a good chair make me more 'productive'? Well, I don't think anyone will argue that I can't type on a e5 Chinese crap one while sitting on a bucket before a door on two sawhorses. I can even type and think equally fast in those circumstances. But better tools still make one more 'productive' in the larger picture, I don't think anyone with experience will deny this either. This 'productivity gain' is in that sense somewhat ethereal, in a poetic sense of that word. To me that's where these tools are at now.