According to recently interview with Tamron executives at CP+ Show several weeks ago by dpreview, Tamron is ready for Canon full frame mirrorless cameras, they will create Canon/Nikon versions of native E-mount lenses with same design.
From Tamron Executives:
Very important. Everybody is going to mirrorless. Canon and Nikon will launch full-frame mirrorless cameras, probably in the near future. When this happens, we can easily make Canon and Nikon versions of our [native] E-mount lenses. The same design could work for [multiple mirrorless mounts].