Here's what I'm trying to understand: On one hand, it seems like large discoveries could be increasing due to more people looking, more earth-moving projects, more development, etc. On the other hand, I could see the big finds decreasing if we had already found most of the big ones (just like there are few large oil fields left undiscovered and so the rate of discovery slows). And on the third hand (?), we're paving over and building on top of a lot of potential sites, meaning nobody in our era is likely to find them, but perhaps some future archaeologist studying our epoch will.
I'm trying to understand what the future might have in store, specifically, a slow down of big finds, or an increase. If the latter, at what point can we confidently conclude that there really are no more major finds left to discover? Implicit in this question is A) the assumption that the potential discoveries are finite, and B) we'll never find them all, but we will approach some asymptotic maximum percentage.
Sorry if this question is inappropriate; I couldn't really tell from the rules whether the current state of historical research is fair game. (Is this a historiography question? I'm often a bit fuzzy on the boundaries of that term.)
Let me explain with an illustration: When Clarence Fisher of the Oriental Institute excavated Tel Megiddo in the 1930s, he did it with huge teams of workers who were paid by the quantity of dirt taken away. When I worked on a fairly large excavation a few years ago, I was one of about eight groups, had a team of two to six workers depending, as far as I could tell, on whether there was a wedding the night before, and I excavated a ten by ten meter square down about a meter over the course of eight weeks. Nobody, or almost nobody, has the sorts of teams that they used to have, and anybody digging as fast and carelessly as people used to would lose their funding very quickly. In some ways the last person to conduct digs in that way was Mortimer Wheeler, who managed that speed partially by being less precise than today, but largely by being a warlock.
But as importantly, research aims have shifted. There are still definitely headline grabber sites, but I would say most archaeologists would agree that the bag of black pepper found in a Romano-British site earlier this year is just as (I say more, but I am biased) fantastic as a set of gold plates. After all, everyone knows that the Romano-British had gold, but Indian black pepper?
This isn't to say that incredible things aren't still being found. As obnoxious as the media circus around it is, the Amphipolis Tomb in Greece will probably yield some spectacular items. The new excavations as Hisarlik (Troy) have been pretty impressive, some of the most gorgeous bronze age material anywhere on the planet has been turning up at Jinsha, and I would say these images taken in the past few years are as spectacular as anything from Howard Carver. There are also things we know about but haven't, for on reason or another, excavated. The Tomb of Qin Shihuang is probably the most famous, but even on a less spectacular level, one of the largest villas in Britain having one of the most intricate mosaics, Woodchester, was partially dug in the eighteenth century, had a couple minor test trenches in the eighties, and hasn't been touched since.
So I would say that there are still amazing things to be found, but archaeology as a whole has moved away from massive projects on spectacular, headline grabbing sites. Also, I mean, c'mon. Tell me this isn't at least as good as Ur.
It's not that we aren't finding new and important things all the time. The really amazing and big finds are on a smaller scale than they used to be. The discovery and opening of King Tut's tomb was a big deal because it was the first time such a thing had happened where there was media coverage that went throughout the world. Kinnewick Man was a big deal because it was the beginning of American Archaeology having to state outright that we have a responsibility to the indigenous peoples (even if Kinnewick Man is scientifically wayyyy to old to align with a specific known Indian Nation).
There are also many more active folks in our field now, which means that many of the big finds are either lost "In Publication" or are only presented at conferences.. the many, many conferences of every size and shape. Other big finds are just part of individuals graduate work and gets forgotten because nobody gives a damn about a Master's Thesis and Dissertations are too much trouble to get a hold of. As we continue to develop the field, more and more specific niche studies break off and the interested parties grow smaller and more periphery to the central, popular studies (these big finds).
Ultimately, there's no so much of a slowing down of good finds, but that they're just not as widely reported. The vast majority of Archaeology in the United States is done by private CRM firms so that a road or pipeline or hotel can be built. These jobs are quick-and-dirty because the funding is limited and the work is a formality in this country.
I think that the future of Archaeology, in the US at least, will see a continued specialization where the big finds will be announced within our niche groups. A lot of really cool stuff just won't be published in a wide-reaching medium (as it is now with most CRM reports). That's not to say that the big finds won't still be available, but you'll just have to look a little harder. Of course, "big find" is kind of a loaded term, given that the popular media sources that make finds "big" (e.g., National Geographic, Archaeology, Popular Science) are more concerned with stories they can make appear exciting, rather than what may actually be exciting for folks within the field.