Apple does not pre-announce end-of-support for any of its products.
That said, for iPad, history demonstrates that the majority of iPad models receive update support for five to seven years. When update support ends, iPads remain usable for as long as third party Developers continue to support older versions of iOS/iPadOS.
As for trade-in opportunities, Apple’s own trade-in programme will generally accept devices that are not current model - and are still eligible for hardware support. The trade-in value, if any, is always significantly less than the purchase price - and the potential value will fall as the model gets older.
You check eligibility for trade-in and obtain an estimated trade-in value for any model of iPad here:
Apple Trade In - Apple
Apple also describes eligibility and availability of service for older devices here:
Obtaining service for your Apple product after an expired warranty - Apple Support
In summary, while the end-of-support date for an iPad10 is unknown - and given that the iPad model is less than an year into its life - you might reasonably anticipate a further five to six years of update support from Apple. Even when support ends, the iPad will continue to be useful. Ultimately, the overall useful lifespan may be determined by the specific Apps that you use.