Some large communities have migrated by force previously. Not that it's any good, but communities.win (or whatever they go by now) does seem to have maintained

Some large communities have migrated by force previously. Not that it's any good, but communities.win (or whatever they go by now) does seem to have maintained its population of right-wing refugees, /r/drama seems to be keeping their own site afloat. /r/startrek set up their own Lemmy instance, so we'll see how that goes over time.