A similar fate will befall Lemmy at some point, so enjoy it while you can.

press x to doubt.

Seriously, there's a low chance for that.

• lemmy is not a service but an open source software
• public lemmy services are ran like a "public service", for the benefit of the public. an instance cannot just lock down its access to users without exiting the federation. and if it exits the federation, it will become worthless basically, as they'll lose all the external content. yes lemmy.ml and lemmy.world are too big, which is a problem, but I don't think they could pull it off easily either.
• lemmy developers are loudly marxist, they oppose capitalism. so both the software itself, and the lemmy.ml instance are unlikely to change in the way you tell