According to latest rumors Tamron will announce 16-300mm lens for APS-C DSLRS in Q4 2013, The 16-300mm will cover a vast range under affordable price, no more info is available.
Last year Nikon announced the Nikon 18-300mm f/3.5-5.6G AF-S DX Nikkor Lens (see at Amazon), its a perfect time for Tamron to announce a alternative lens at an affordable price.
If, a new lens going to release soon or later at f/2.8-4.0 without any complication for IQ Tamron will hit the home run on their new toys… 😉