I think this would not make too much difference. Some wifes/kids/friends will get EBG but it would remain just another plastic card for most of them. If people not flying enough to make gold themselves, they would not start flying more just because they've got EBG. And not so many chances some of them would be able to re-qualify next time, well ok may be some who was around silver level with some other carrier will switch to EBG as it will be easier to maintain.
But generally speaking more members = less privileges.

Not sure if this was covered before, but there are some ways of how you can get EBG without flying at all. I know Diners Platinum in Finland is accompanied by EBG card which (I think) is valid through diners validity. Any other examples?