Ellice island-
There seem to be two facets to your question- where is the collection of warbirds as trophies/trinkets/museum pieces going, and where is the collection of warbirds as flyable aircraft going. Both are important questions, with a variety of potential answers, but with very different implications.
If you are after a serious response to your question (which I think is an important question) you might consider asking Mark Clark, the owner of Courtesy who does post here from time to time. Mark has been in the business for decades, and probably has the appropriate long-term perspective (as well as the insider knowledge that comes from transacting in warbirds with some of the most well-known international pilots and collectors.) If he chooses, I'm sure that he could provide a thoughtful response that might answer your question.
BDK and Spanner, on the other hand, are just being pessimistic and cynical...

(or is that just cleverly disguised optimism?)
As someone who has neither the cash nor the piloting skills to own and operate a warbird right now, I am just thankful that there are those who commit the time and resources to maintain and fly these treasures.
kevin