Wow, that is heavy news! Even if I never bought a single part via Bricklink. I can simply not immagine that this can have a great outcome in the future. Of course there would be a lot of great new opportunities that I could imagine out of this new ownership. Buuuut I can also think about far too many not so nice things happening which would not make it worth it.
But also, I mean I can totally understand why they see the need to get better connection with Afols.
Right now there is a bigger and bigger growing pool of other, mostly Asian, Lego-like manufacturers. And what they do is simple but effective: They produce the stuff that Afols want. Sets that have 6.000+ or whatever pieces and look like Mocs. They are often beautiful, even tho the quality seems to be rather not so up to Lego standards.
Buuut people buy them because they love the looks of these and because they are often the stuff that Lego does not produce. And even tho a lot of these are stolen designs and shit quality. People rather buy 10 of these then 1 Legoset. Because the prices allow to do so.
Sooo to keep up with the wishes of more and more Afols that love beautiful Sets rather then stuff like a Hoth UCS or whatever, they see the need to get into the core of the Afol community and with Bricklink they probably see a way of making it possible to even sell Afols Mocs without loosing out on profits and competing with the Asian Manufacturers.
Still I see a lot of downsides (some of them allready posted by other people above) and I now can only hope, that somehow non of these will become reality...