Switch will outsell 3DS and Wii U combined so in that sense yeah. It probably won't outsell DS + Wii though.
Yeah but that doesn't mean it will make more money.
Double devices means:
Double the marketing, production costs, studios developing games from the same series for weaker and more powerful devices, etc.
What I wanted to do was look at their profit after expenses were taken out to see if they are doing better financially than when they had to double all those things and the evidence points to a resounding yes.