You seem not to understand why Apple even offered the iPhone 8. They offered the iPhone 8, because they know the iPhone X is not affordable for everyone. Not to mention, Face ID would not be widely adopted when it was first announced. The iPhone 8 is an alternative to that. But touch ID altogether ultimately will be discontinued and Face ID is their future.
If Apple offers an iPhone SE 2, it may retain touch ID, because it's an entry-level/budget iPhone that does not adopt the latest Hardware features.