Currently Online 
Of course it won't sell less than WiiU. With the Switch Nintendo combined their mobile audience with their console audience. WiiU was still sitting next to 3DS.
Selling out before release doesn't mean anything, it's the same with every console released. XBox Series included.
Xbox Series X/S Pre-Orders Sold Out in Minutes As Expected & Twitter Reacts Accordingly
https://www.newsweek.com/xbox-series-x-s-pre-orders-sold-out-error-loading-1533616
Anyway the fear of price hikes is real now. Recent consoles have only gotten more expensive during their lifetime and now with tarif threats it could be any time. Better pre-order at $450 instead of risking having to pay $600 later...
So no, pre-orders selling out is zero indication of how a console will do lifetime.
