The only reason severs were shut off every generation was due to the free nature of Nintendo's service, it wasn't economically feasible to keep servers up on games that weren't being sold anymore. Now, they will have a cash flow large enough from subscriptions to keep switch games up definitely after another system launches, and will probably keep Wii U servers up too as a result. Look at how PS3 and Xbox games still have several due to PSN and Gold. If they don't do it with Wii U, they surely will from now on.
Edit:spelling (probably still screwed up somewhere)
Discussion started at here by onehandsomegamer