WiiU and 3DS had droughts and sometimes even aligned.
Genres and gameplays that thrive in console and hand helds are different. So I think it will add to identity problems. And probably most of WiiU owners have a 3DS so it will shrink userbase and will lose double dips from games like mk and ssb.
And if they decide to release a single sku that you have the console portion on TV and portable as control akin WiiU (but able to take with you standalone) it costing 200 would make it too weak to be worth as console, but good as secondary.
Maybe if all conditions on the ideal world you described happen they may be viable. But from what I see with the userbase this gen Nintendo is losing Money, if smartphone eat more sales from hh and Sony MS robs more mindshare in consoles, I could see Nintendo selling no more than 60M NX and 300M SW on the gen, not sure if enough to be successfull, but certainly good for survival if managed right.
duduspace11 "Well, since we are estimating costs, Pokemon Red/Blue did cost Nintendo about $50m to make back in 1996"
http://gamrconnect.vgchartz.com/post.php?id=8808363
Mr Puggsly: "Hehe, I said good profit. You said big profit. Frankly, not losing money is what I meant by good. Don't get hung up on semantics"
http://gamrconnect.vgchartz.com/post.php?id=9008994
Azzanation: "PS5 wouldn't sold out at launch without scalpers."
