Bashiok has posted about end game solutions on the official forums. Looks like we will be seeing changes to end game in upcoming patches, as well as PVP in 1.1. Below is the full post.
Blizzard blue tracker: July 4, 2012.
We recognize that the item hunt is just not enough for a long-term sustainable end-game. There are still tons of people playing every day and week, and playing a lot, but eventually they're going to run out of stuff to do (if they haven't already). Killing enemies and finding items is a lot of fun, and we think we have a lot of the systems surrounding that right, or at least on the right path with a few corrections and tweaks. But honestly Diablo III is not World of Warcraft. We aren't going to be able to pump out tons of new systems and content every couple months. There needs to be something else that keeps people engaged, and we know it's not there right now.
We're working toward 1.0.4, which we're really trying to pack with as many fixes and changes we can to help you guys out (and we'll have a bunch of articles posted with all the details as we get closer), and we're of course working on 1.1 with PvP arenas. I think both those patches will do a lot to give people things to do, and get them excited about playing, but they're not going to be a real end-game solution, at least not what we would expect out of a proper end-game. We have some ideas for progression systems, but honestly it's a huge feature if we want to try to do it right, and not something we could envision being possible until well after 1.1 which it itself still a ways out.
Auction House or Not Web App
Also check out the Auction House or Not web app (made by postm) that we added to the tools section today. It helps you determine quickly and easily whether you should sell an item on the AH or vendor it. We already have a great Auction House, Salvage or Sell guide in the guides section, but this tool makes determining what to put on the AH even easier. Note when using this, make sure you use it as a starting point, not as a final say in whether you sell an item or not. Always double check on the AH to make sure the item you have isn't worth a lot before scrapping.