The Joycon controller is no where near the quality or comfort of the pro controller. And if these people wanted to play a game on the go and they would be part of the handheld market, which they aren't.
I can't give you a number, but it's obvious that BOW has a market for gamers who don't currently own a Nintendo console, or don't plan to get one.
Those people wouldn't be handheld gamers in the past, because before Switch there was no such thing as a high quality open world RPG on a portable device. You cannot draw a definite conclusion that they have no interest in portability when we haven't had a scenario for a proper analysis yet.
I asked you for an estimate. You proposed that Nintendo should cripple their Switch marketing message in order to appeal to such gamers. You took issue with me saying that you are unreasonable. You kinda have to throw out a number to have any sort of argument, but I suspect that you begin to realize that your proposal didn't make sense. You'll be either stuck with a number that is too low to justify the obvious drawback of your proposal or you'll have a number that makes you prone to get ridiculed.