The lens mounts are identical!
The difference is the a6000 is a 24 mpxels cropped sensor, the a7 series are 24 mpxels full frame. Some lenses are for cropped sensor, some are full frame.
Once again it's the same mount.

Cholly, I'm beginning to wonder if the confusion for so many people starts with a "Nikanon" mindset. Until one sets his or her rigid DSLR point of reference aside, (s)he'll not "get" the Sony mirrorless systems. Do ya s'pose?

Oh, bull! Who are you, or who am I, to pontificate about what the "serious photographer" (the phrase itself smacks of arrogance) wants or needs? I've sold lots and lots of images, seen my images on over a dozen magazine covers, and had hundreds of images used in magazines; yet I own two bridge cameras, including a P900. None of us is more serious than the other; we come to UHH to share and grow, not to have some sparrow-fart tell us what camera we should own.