This would be an extremely useful tool for smaller streamers who benefit from viewers seeing sub goals.
The way it'd work is you would set an increment amount. Say 5. So if you select five, the goal would appear like this:
Gain 5 subscribers, and it meets the goal, raises by the increment and now shows this:
If you already had a decent sized following you could raise it even higher, say 25 incrementally. IE:
You could even add options for Daily/Monthly/Session sub goals and allow for the incremental increase.
Foundationally it'd at least be nice to have a supported subscription goal bar, something you could set and change on your own at least.