Personally, I would love for virtual caches and webcam caches to come back again.
Virtual caches are really good to be used in nice places that you want to show to other people, but can't leave a physical cache. Either because there are far too many muggles around to be able to log unnoticed, or because placing a physical cache would disturb the environment (like in nature). The few virtual caches that are left now usually are at really interesting places, and because of that I really love doing them. A couple of years back, I even made a long trip through the Canadian Rockies mostly following virtual caches and (old style) earth caches, that brought me to very interesting and fun places not mentioned in any tourist guide at all. That was a very fun experience.
As for the webcam caches (like for the virtual caches), I can't see why they were abolished. These too are often in fun places like old style city centres and fun to do and see, again because they usually bring you to nice and very unexpected places. However, I do know of at least one "new style" webcam cache, that is published as a traditional cache, but gives you the opportunity to have your photo taken on the spot by a webcam. See "'t Nessie". The listing doesn't reveal anything about the webcam, but find the cache and you will find the directions on how it works.
Both of these cache types have a lot of (fun) value added above the other cache types that are still available. They add enormously to the experience of caching - and as a result to the whole trip. So for me, having them back would be really good. I use them to plan routes when I travel around. And I do know of some places I'd love to show to people, but can't do now because no physical cache can or should be hidden there.
As for Groundspeak: I don't know what their exact thinking was back then to have the creation of these new caches halted. And since they are usually not very talkative about future plans, just don't expect these cache types to come back. But I personally would love to be able to publish new ones. I think "new style" virtuals where you have to send in an answer to the CO as like we have to do with earth caches would be good to have. Possibly even to have them divided in subject categories like "(virtual) nature caches", "(virtual) history caches" etc. Webcam caches can come back simply as they used to be I think, maybe with some restrictions added as to a certain quality of the resulting photos.