so with dominion gone, what is going to happen with dominion tower capture champ animations?

You're implying Riot has actually put some forethought into one of their actions.

Let's not give them too much credit now.

They're still currently used for Rek'Sai tunnels and Skarner shrines and supposedly Thresh lantern. It'd be interesting if Riot decides to cut back on (future) costs and remove those animations as well.