As long as 3DS game development does not interfere too much with the Switch's software output, it seems like 3DS+Switch is a relatively viable strategy (for the time being). Of course, the 3DS and the Switch will be competing with each other, a negative byproduct, but the Switch is close enough to a home console experience, and is being touted as such, to give it a distinct and seperate appeal to consumers.
The most likely resolution here is that Nintendo is going to stop developing 1st party titles for the 3DS after 2017 in order to focus on the Switch, but will not discontinue the 3DS platform ($$$).
bet: lost







