Idk if reddit will actually "die"
I think it depends on us users. If we can make a community work here in the federated space well enough to draw users then reddit might really go away.
But if they manage to kill off 3rd party devs, APIs and etc quickly before these alternatives are baked enough to work for their users and these existing federated tools aren't good enough -- then they'll just maintain via the network effect.
for me its the top left panel being partially shaded. thats going to really reduce its functionality.