I was one of the folks that was mightily disappointed when the Nentir Vale Gazetteer was cancelled;
Actually, I was glad of this. One of the things I liked
most about PoL-land was that it was left undefined, and so open for the DM to do what he liked with it. I always felt that the more WotC fleshed out the Nentir Vale, the less utility that setting had. (And for those who
wanted a detailed setting, there were plenty of options out there...)
Which is where the plea comes in. Dearest Wizards of the Coast, please can we have a new campaign setting for 5th edition? My recommendation would be to have two parallel publication lines for setting:
1) D&D Classic Settings...
2) New Setting (or two)...
The problems with this are two-fold:
1) The majority of gaming groups don't use
any setting - they homebrew, or don't give any great thought to the setting at all.
2) Even those groups who do use a setting typically only use one, so multiple settings inherently compete with one another.
During 3e days, WotC dealt with this through three mechanisms: firstly, they concentrated all of their resources on a single* setting (Forgotten Realms); secondly, they priced setting books at a premium, so that they had to sell fewer copies to make them worthwhile to publish; and thirdly, they filled those setting books with a great deal of 'crunch', meaning that they were of significant use to people who
weren't using the setting - the FRCS for example contains dozens of races, spells and magic items that can be used just as easily in a Greyhawk/Eberron/homebrew campaign.
* Of course, you're going to point out my mistake here - Eberron. However, Eberron was very definitely a special case. Firstly, it came late in the edition cycle, when the FR releases had distinctly slowed down. Secondly, and probably most importantly, Eberron had
massive hype due to the "Setting Search" competition that WotC did. This more or less guaranteed that Eberron would be a hit, at least in those first few releases.
The upshot is that I would be
very surprised if WotC provided significant support for any setting beyond FR (though there may well be a 'default' setting in the core books). Even the 3-book model from 4e looks unlikely to continue - after FR, Eberron and Dark Sun, they seem to have abandoned it.