There some ideas i found by myself.
Invite URL Links
Invite people from URL can be such a great idea for TS5 Users. When the web client will be avaiable, the invite links can be handful for all. Same functions to Discord but with a touch of TeamSpeak.
Bots and API
I know how much people needs a bot music inside thier channels. Soo if Teamspeak open a Developper Portal for creating bots and some apps that use the SDK of TS can be a great idea and make TS login for some communities and games launchers like Steam or others platforms and for integrations for example. For bots, they can be handful for every task you needs to execute, like a AutoMod, music or something else.
And Teamspeak aleary got thier SSO. Soo why not?
System Theme Sync
I feel this will be missing. Why not sync night mode with Windows system settings? Handful for people who want save times under set-up night mode every apps.
Automation commands for servers
That can be such a replacement to bots. Config some limits, or when someone interact, that does a thing. (Reference to IFTTT for people who wants to see whats i talk about of this section.)
I hope the idea can be handful for all. Maybe TS can let’s people host bots and servers inside thier computer or from a host services. No one know, but these can be handful.