This thread gives me a headache. It's not that complicated, economics 101 supply and demand. Here is a couple scenarios of what could happen.
1. Ford makes a low production V8 raptor in 2021. Prices for those will be top dollar, but since it will be a low production truck, won't effect the V6 Gen2 much if anything. V6 raptor still an awesome truck for 99% of people and will depreciate at its current rate it is now.
2. Ford makes a high production V8 Raptor. Probably about 1/4-maybe 1/2 tops, of current raptor owners trade in their current truck whether its a Gen1 or Gen2 for new V8 model. Prices depreciate slightly more than they are currently but not much. Gen 2 V6 still an awesome truck that many people would want used.
3. Ford doesn't make a V8 Gen2 ( which is 99% most likely going to happen). They keep the V6 in their Gen 3 Raptor. Current Gen 2s depreciate like normal and life goes on.
People forget these are toys, nobody buys a raptor because its practical. If you want a car that will not depreciate much no matter what new models come out and is practical, go buy a honda or kia or something. You buy a raptor because its a bad ass toy, and news flash, toys go down in value because everybody wants the newest, baddest toy. You want to talk about depreciation? My Mclaren 570s brand new sticker price was $228k, I picked it up 3 months after it was delivered as a demo car with 1,000 miles on it. Picked it up from the dealer for $180k. Thats $48k depreciation after 3 months and 1,000 miles. Still comes with all the perks of a new car and warranty and everything.
So to sum up my thoughts, regardless of what happens if Ford makes a new V8 model or not, your Gen2's value will be fine. Its a bad ass truck that is VERY desirable on the used market that almost everybody would want no matter what happens. End of story.