I'm afraid that no-one here can tell you anything about Apple's unannounced plans in respect of the compatibility of Apple Watch Series 2 models with future software versions or about hardware support, beyond the Limited Warranty period.
You are not talking to Apple here - this is a user-based technical support community.
Apple no longer sells new Apple Watch Series 2 models and instead sells a newer model range, Series 3. Differences include that Series 3 models have a faster processor and a more power-efficient Bluetooth / Wi-Fi chip than Series 2 (and Series 1) models:
Series 2 models may still be available:
- To buy new from some Apple Authorised Resellers.
- To buy refurbished from Apple:
In the US, for example:
- To buy pre-owned from private sellers:
Keep in mind that Apple Watch Series 2 requires an iPhone 5s or newer model, running the latest version of iOS 11.x:
Set up your Apple Watch - Apple Support