Seasons and Tiered Rifts announced

http://www.diablofans.com/news/47996-confirmed-season-and-ladder-like-system-in-first

I believe this was from the launch interview with Josh Mosqueira and Wyatt Cheng (I had the live stream audio turned down though since I was playing, and didn’t really hear much of it).  Both are slated for the first major content patch for the expansion (probably summer).  I actually came pretty close as far as calling the ladder system they are going with in this forum post:

http://us.battle.net/d3/en/forum/topic/12081718116?page=4#64

What I posted:
Initially, I thought it would have something to be with online profiles (giving them a bit more love than what currently exists).
After reading Don Vu’s tweet with the missing 7 letters – https://twitter.com/donvu4u/status/443976633876099072
It’s probably hinting at Ladders; though it will probably be called “Seasons” instead (so it will be different than the sort of ladder system that existed in D2; it has to be due to technical issues with the game design). Part of the work/content is already done with the work they did on Nephalem Trials; some of that they put in patch 2.0 as Cursed Shrine/Chest events. There is also past datamined data showing artwork related to PvP; which can be repurposed for a Player vs Monster/Environment vs Player sort of competitive challenge races/event system. I’m sure that such a system will include individual type of races (like who can do the quickest full clear on Torment, who can reach Paragon 100 first, who can get the highest Paragon level in a season, who can kill the most elite packs, etc – basically, anything that can be viewed as an achievement, would be viable in this system).
The important part that is missing is the tracking/rewards system which led them to not include Trials at the release of Reaper of Souls.

Posted by Lylirra 

Nephalem Trials are indeed still alive in some form, but they will not be added with the launch of Reaper of Souls. We absolutely love the idea behind the Trials (challenge-based systems can be so much fun), but before we implement them we want to make sure they have a strong underlying reward structure and tracking system. That kind of hook is important for a system like this and we didn’t want to add in Nephalem Trials to the game without it. 

The gameplay felt great and was in a good place at gamescom 2013 where we announced them – which is actually why a lot of the individual Trials have been added on their own as standalone events into Reaper of Souls – but the tracking mechanism that made the overall system feel meaningful over a long period of time wasn’t and would take some pretty significant tech and time to implement (in this case, at the expense of other features as well).  

Rather than delay the release of the expansion to make sure Nephalem Trials could make it in with all the necessary components, we made the decision to cut them for now and re-focus our efforts on making sure other key systems like Adventure Mode, Bounties, Nephalem Rifts, and Clans & Communities (just to name a few) are solid. It’s not an ideal scenario, but these are the kinds of hard calls we sometimes have to make in a world where we can’t stack +Maximum Resource. >.> 

Edit: For clarity, Nephalem Trials are not Nephalem Rifts. Nephalem Rifts are definitely still in the game!

Source: http://us.battle.net/d3/en/forum/topic/10491039663#7

They also have some code that can be repurposed for that (the score board system used in Team Deathmatch). Ladders/Seasons is somethings that requires integration with Battle.net 2.0. If done properly, it could also be inclusive of Clans (so not only individual PvEvP challenges, but also allow Clan competitions), and also provide more online profile/armory functionality by pulling not only achievements, but ones individual season ranking details (in addition to the overall leaderboard).

In a nutshell, it’s easier/more cost effective to re-use/leverage current content and systems.  Also, while you basically start from scratch in a season, any Paragon experience earned, will go over to each modes (normal or hardcore) account wide Paragon (as opposed to moving an entire ladder character over to non-ladder after a season ends).  Thus Seasons provides the challenges/competitive angle, while still contributing to your overall experience.  It also deals with the technical/design limitations (including limited character slots) of the game.
What may turn off some folks to this is that it may feel somewhat mandatory (due to Seasons exclusive legendary items).  The specific details are lacking though (like whether or not, these season specific drops, will eventually drop in the game after a season ends – if so, then it isn’t mandatory – its just that these specific rewards are delayed content for non-Seasonal characters).

Basically, Seasons is going to cater to many different demographics like those who enjoy re-rolling, achievement hunting (as you can kill two birds with one stone), enjoy cosmetic type of rewards, enjoy challenges, enjoy the competitive aspect of being seen on a leaderboard.

Myself, I’ve always found leveling in Diablo III, more enjoyable/rewarding compared to max level game play (part of that however is due to the lack of stuff to do once you’ve played at max level for awhile).  Seasons is the type of system that I’m looking forward to (the devil is still in the details though with the actual implementation), and will give us something to do with the gear that we find.