At its current pace it's poised to outsell the Wii by 2021. It will likely have continued support for at least another 5 years. When it's all said and done I wouldn't be surprised to see its lifetime sales sit at 105M+. Of course it all depends how big of a chunk the Switch bites from its pie.
That would be pretty crazy. Playsation would have the 3 best selling home consoles of all time. Ironic Nintendo who used to be synonymous with gaming contributed to the birth of the Playstation brand.