Discord doesn’t have the client API like what TS has to make TokoVOIP, and thus anything built off of it to work.
TS isn’t outdated, Discord is just far easier to use. For anyone who wants to control their server, TS is still one of the go-tos because of its quality. The only thing that’s outdated about it is the UI … which is all personal preference.
Yes, for it to function as an actual in-game VOIP replacement it would need to be able to adjust client voice volumes and control which channels you’re in. Something that you cannot do with Discord.