Mattel finally issued a statement on the future of MattyCollector.com… And it’s a bit vague.  No mention of the future of the Thundercats line and while they announce that Super 7 will “take over” Masters of the Universe … It never specifically mentions MOTUC. 
See the press release below:

To Our Loyal Collectors,
Thank you for being the world’s most dedicated fans and passionate supporters of MattyCollector.com over the years.
We want to let you know that we have been working on something new and different for you that measures up to your loyalty and devotion.
As of December 31, 2016, we will be shutting down the website as we transition to Super7 to manufacture and deliver the Masters of the Universe and adult collector lines. Subscriptions and orders for 2016 will remain unaffected, and the site will continue to operate through the end of the year. For the past two years, Super7 has proven to be a great partner, and we look forward to seeing them continue to grow the Masters of the Universe line. They will unveil the expanded line for 2017 at San Diego Comic-Con.
To help you complete your collections before the end of the year, we’ll be opening the Vault beginning Thursday, July 21 at 9 a.m. PT. All 2014 and 2015 items, and select 2016 items, will be available for sale at that time. They’ll remain in the shop until the end of the year or while supplies last, whichever comes first. For our U.S.-based collectors, any Vault products you buy during San Diego Comic-Con will arrive with free domestic ground shipping.*
We thank you for your dedication and support through the years.
Sincerely,

MattyCollector.com

 
*Free domestic ground shipping offer on all Vault products ends 7/24/16 at 11:59pm PT. Not valid on previous purchases. May not be combined with any other offer or discount. The discount appears in your cart when you add your first qualifying item to your cart. Applies to standard shipping only, and excludes rush orders and additional shipping charges for international addresses.