We can't really compare the support Switch will have after the successor gets released to the 3DS after the Switch.
Nintendo was coming out of a tough generation and 3DS was their pillar to stay afloat. Switch was a big turnaround for Nintendo in terms of market position, how they consolidate their teams and games on 1 system. I think they were scared it wouldn't pick up in the first year and so they could have relied on the 3DS a bit for income. They were totally different system anyway so they could afford to still have it on the market cause it wouldn't overshadow or compete with the Switch in any category.
But with a Switch successor.... it will definitely just be a Switch with boosted specs, probably more features and more premium design i guess. It might be backward compatible too. I doubt they will keep Switch around as much as they did with the 3DS and will instead want people to move over to the new one. Another important point is Switch never got a price cut cause it could sell without it. It for SURE could be sold at like 200$ and still make a profit. But it's still at it's original price. Nintendo is always really careful on their pricing and they won't put the successor at more than 400/450$ imo. Maybe 2 models like 1 for 400 and the other for 500$... but i think 350-450 is the sweet spot. Now why would they keep supporting the Switch ? It can confuse the consumer and maybe make him buy the cheaper one. With the install base of the Switch, they will probably do some big cross gen games. If they wanted to keep the Switch, i think they would have reduced the price this fall to make it last for a little while with the successor. But keeping it at the current price... to me it just sounds like they will fade out the Switch and move on. They won't cut the price of the Switch a few months or when the successor releases so the consumer buys the new one.
So i was open to seeing the Switch become the best selling system but seeing how Nintendo isn't really aggressive even on it's last holiday season on the market... i feel like they don't care and are ready for the next thing. That will for sure cut the legs short on the Switch and i expect it to sell around 150-152 millions lifetime.
