My main questions and comments are simply about the extent that professionals do or do not in fact use DMF equipment rather than using a smaller format like 36x24mm. So my apologies for following the red herring about "need", which is neither particularly relevant to my point nor within my expertise. So let me focus my curiosity on the patterns of equipment choices that are actually, currently being made in various areas of professional photography.
To KLaban and Bernard:
Although my impression is that there is still a significant amount of professional usage of DMF cameras (i.e., the DMF market is not so dominated by wealthy amateurs), that is mostly anecdotal, not based on hard data. My "equipment egalitarianism and progressivism" certainly makes me hope that the actual need for such bulky and expensive gear has been reduced to a very low level by recent technological progress. I am comforted for example that a chunk of professional work can be (and occasionally is) done even with teeny tiny 4/3” format, even though that removes any gear-based excuse for my less than professional quality results.
But as one datum on actual current levels of professional DMF usage: one of the forum members who deals with DMF equipment recently indicated that rentals are a very large proportion of their DMF business, and since I doubt that many amateurs rent DMF gear, that suggests to me that there is still "significant" professional usage of DMF.
Maybe insiders like Doug or Steve or Yaya or Thierry or Stefan could add some facts here!