It will if Lemmy becomes successful. It will have to stay tiny and very niche. Or else all communities have to deal with Eternal September if they start getting a lot of users. Then communities will gravitate towards the same lowest common denominator content and comments seen elsewhere.
Nah, that's the whole point of federation. To keep it from becoming Reddit. The problem with Reddit isn't that it's big, it's that it's highly censored on a wide variety of topics that aren't anywhere near offensive but simply counter to Western hegemony.