i would love to see:
- higher audio bitrates than current ~96kbps
- official support for making music(and ofc chat, bots for many purposes in general) bots (so attaching ts client and doing other tricky stuff wont be needed)
- screen sharing
- video sharing
- saving chats server-side as an toggle per-channel (toggle just like “use as default channel”)
- custom emojis/icons on the chat
- colors & newlines for join modals so it looks the same on ts3 and ts5
- “embedding” links/images(from url)/videos(from url) on the chat, so for example sending https://teamspeak.com will embed the site metadata (just like youtube videos embed), platforms such as discord offer that and its cool
for servers it could be a setting in server settings under something like “media proxy” - loading images on the chat automatically and embedding video files in the client (loading them automatically aswell)
- “modern” public server listing
- more licensing options, maybe some new features such as upgrades/benefits for something to get more slots and help with imporving and growing the server? I feel like licenses are kinda overpriced in current state
or maybe get more income sources to make licensing better or revamp the system in general? - displaying in-game statuses
- “windowed” channel creating and permission editing (just like it is in ts3) as it is more comfortable for me, currently i hop on ts3 to tweak my server
- maybe text-dedicated channels that you can read from anywhere? (not groups)
- free mobile app
- browser client
- some sort of contacts system for users that are not logged in
- end to end encryption
- integration with services such as steam to add friends from teamspeak on steam faster
- “alternative functions” for users that are not logged in (to “replace exclusive” features for users that are logged in)
- recording voice, maybe also recording screen/video if streaming will be implemented
- display server banners on whole server just like on ts3 as i find it more “fancy”
- plugin SDK that supports more programming languages?
- minimize to tray
- keep myts and server avatars separated
- Make max. displayed icons a setting in the server, not client (under developer tab) so it can “improve” the “compatibility” with servers and its groups
I hope atleast some of those will be implemented 
And also sorry for some grammar mistakes but english is not my native language
