Frank, I see you point and agree to some extent, however I personally have no plans to dump my LA-EA4 anytime soon. I admit that it has some limitations with my A7, principally No image stabilization with A mount glass. I don't know if that limitation could have been avoided if Sony had wanted to. If so then that would help confirm my suspicion that Sony are more interested in selling cameras than they are in keeping loyal customers.
More to the point, the sigma MC-11 Mount Converter together with all the other adapters that are available will no doubt allow Sony to sell more cameras at the cost of Sony E mount lens sales. I can't see Sony standing for that for long though. Lenses are a big part of any camera makers business and I wouldn't be surprised if, at some point in the not so far future, they modified their future cameras to prevent the use of third party adapters. That may or may not be possible but knowing Sony's abilities and propensity for innovation, I am sure it is. They still have to build up their lens base for mirror-less cameras and these third party adapters help keep them in the game until they do so. But make no mistake, that is probably the only reason they are allowing it. Some time in the future they will correct that, as I said above.
Then again, perhaps Sony have decided to be good guys and help Sigma, Canon, Nikon and all the others sell lenses, while they concentrate on cameras only? Somehow I doubt that, Sony want it ALL.