Legacy emote slots
How about "legacy" emote slots?
If you have subbed for a year = you get an extra emote, 2years = a second emote etc.
You unlock them by either having a streak of 1 year/ 2 years etc (and then the user can keep using them even if they aren't subbed anymore. Just like unlocked bit emotes that stick with the user.)
Or unlock by being (with breaks, but in total) subbed 1 year/ 2 year etc and only get access to the emote when you are subbed.
Would be a cool reward for long time supporters.
Original idea by Twitch user @Chromerian_