Actually, Intuit has been developing a new version of Quicken for Mac for the past year. They're building on the more modern Quicken Essentials code base, and adding the functionality from the legacy Quicken for Mac products (like handling investments). The first release of the new Quicken will probably occur this quarter, with additional free updates in subsequent quarters as they continue to add functionality.
Is there any actual confirmation of this? Quicken Essentials for Mac was introduced in February 2010. We're about to enter August of 2014. They couldn't add features - which they had already designed and coded - into another product in less than three and a half years?
I think there were changes in personnel, and the team that built Quicken Essentials was not kept intact to continue development. And they spent a significant chunk of time writing the code to enable Quicken 2007 to run on Lion (and Snow Leopard and Mavericks, and, from user reports, Yosemite) after Apple removed Rosetta code from Lion.
A new product manager was hired in 2012 (from the Microsoft Mac team), and they began working on the foundations of a new Quicken for Mac, built on the work that had been done for Essentials. The guy's name is Marcus, and if you Google "Quicken Marcus", you'll find his postings in the public Quicken Community forums. (He also tweets periodically, with the handle @softwaremarcus.) Here is a good post to start on, because it addresses why they couldn't replicate Quicken 2007 or Quicken Windows for a new version on the Mac:
The latest of the public posts is a few months old, but talks about their progress in early beta versions of the new version of Quicken. Development has continued since then, and more betas have been released to testers who are doubtless under non-disclosure. From what I've heard, they are pretty close to releasing Quicken 2015 for Mac. It's not going to be feature complete in the first release, but they must want to get it on the market a.s.a.p. as an update for Essentials users and others eager for Quicken on the Mac. They plan to have free updates throughout the first year to add additional Quicken 2007 and Quicken Windows features which haven't yet been built in Quicken 2015 for Mac.