Hi
All bands that are currently available to buy from Apple are detailed here (for the US, for example), with size details provided on their respective product pages:
Stated wrist sizes relate to the wrist circumference that the combination of band + case is designed to fit.
If you would like to submit feedback to Apple, including feature requests in respect of future band designs, then you can do so here:
Feedback - Apple Watch - Apple
I'm afraid that no-one here can tell you anything about Apple's unannounced plans. You are not talking to Apple here - this is a user-based technical support community.