Most certainly if this grows big enough corporations will join in if only to market whatever products to the userbase.
What you can do is to work on supporting/curating instances which don‘t want this. Try to see what kind of people are in charge and what their reaction would be. For example I‘m also on an instance (http://lemmy.dbzer0.com/) created by a r/piracy mod who I‘m fairly certain wouldn‘t federate with corporations or let his instance be controlled by them.
Lemmy.ml which I‘m also on, probably not positive with US companies, but might federate with Chinese companies.
What makes all this not a big concern for me is how easy it is for me to drop an instance and go to another one, but I‘m also not attached to my users in general, hopefully we can get some export/import functions for cases where we need to abandon somewhere (unless it exists and I haven‘t seen it yet?).
Cannibal take seems accurate, kinda how it feels looking in too. Not glad about any of these people in charge, but at least they hurt each other right now.