The Handheld console market is at a low point for potential install base. Nitendo's home console appeal among gamers is relatively low. But that said, combining the handheld and home console market potential for firm Nintendo fans still gives Switch a life times sales potential of about 60-70 million (based on WiiU + 3DS sales, noting that there will have been a lot of people who bought both Wii U and 3DS so the markets are not completely segregated). Switch appears to have a wider appeal to gamers beyond its core of support, so you can ad several million to the "base" level of sales. The question is does Switch appeal to the casual / non-gamer market? I'm not sure it does, to the extent that Wii did.
My guess is Switch's maximum market potential is about at the same level as Wii. But it's far from clear that Switch can reach it's maximum market potential. OTOH Switch's floor is more or less around where PS4 sales are now.
PS4 could reach Wii levels, and possibly a bit beyond. But it's not certain it will.
I think it will be pretty close.
“The fundamental cause of the trouble is that in the modern world the stupid are cocksure while the intelligent are full of doubt.” - Bertrand Russell
"When the power of love overcomes the love of power, the world will know peace."
Jimi Hendrix
