Let's compare 3DS+Wii U vs. Switch. Switch has:
1. True. At an increased price, but still true.
2. So far there's nothing but Zelda. You may argue all you want about promised content in the future, but as of right now that's not really true.
3. See 2.
4. Correct, but then again...was vita really a competition to 3ds? Sure, right now there's really no competition, not even theoretically, but I still don't believe vita took a significant amount of sales from 3ds in order to make this current handheld monopoly a significantly better place for switch.
5. Nothing has gotten better either. People's focus did not suddenly shift towards handheld gaming. If anything mobile gaming is still very much growing.
Conclusion: If Nintendo somehow manages to produce the same support for Switch as they did for 3ds despite the obvious increase in development cost and time then it should see similar sales as the 3ds. If it doesn't - it won't.