On February 1st, 2016 I had a conversation with a Ancestry.com representative and they said multiple software vendors are being worked with to provide access but could not name any of them at that time on each platform.
I also reached out to the makers of MacFamilyTree and they said they have reached out to Ancestry.com since the announcement to utilize the API but so far have not received a decision from Ancestry.com on whether they will be allowed to do so.
On February 2nd, 2016 Ancestry.com did send out the following statement stating at this time there are two immediately available replacement products from Software MacKeiv for and Roots Magic for PC and Mac (see note below).
From Ancestry.com as a follow-up to the original announcement of the end of support of Mac FamilyTree; screenshots not included in original announcement and taken from Vendor's websites.
Today, we are pleased to announce two options for desktop software that will work with Ancestry.
Software MacKiev
Software MacKiev, with whom we have a long-standing relationship, is acquiring the Family Tree Maker software line as publisher for both Mac and Windows versions. Software MacKiev has been the developer of Family Tree Maker for Mac for more than six years and is thrilled at the opportunity to publish future versions of Family Tree Maker for Mac and Windows.
This new agreement means you will receive software updates and new versions from Software MacKiev, and have the ability to purchase new versions of Family Tree Maker from Software MacKiev as they are released. You will have continued access to Ancestry Hints, Ancestry searches, and be able to save your tree on Ancestry with Family Tree Maker moving forward.
RootsMagic
We have made an agreement with RootsMagic, a leading genealogy desktop software program publisher, to connect Ancestry with the RootsMagic software by the end of 2016. With this new relationship, RootsMagic can serve as your desktop family tree software, while having access to Ancestry hints, Ancestry searches, and the ability to save your tree on Ancestry.
Note 1: The note on RootsMagic that it will bring these features in the 'near future'.
Note 2: RootsMagic for Mac installs CrossOver/Wine to let the Windows program think it is in Windows and RootsMagic is not a native Mac application.
Then went onto say....
We have heard your concerns and are working to provide the solutions you requested. These new agreements will make it possible to preserve your work on Ancestry and Family Tree Maker and enable future features and benefits to help you discover your family history. Be assured that Ancestry, in cooperation with Software MacKiev and RootsMagic, will continue to support you as you discover your family history.
We ask for your patience as we work diligently through all the details to make these solutions available. You can find additional details about these Family Tree Maker partnerships on our blog. We also encourage you to continue to check back on our blog for future updates in the coming months.