@picandocodigo it's averaging about 20M units a year, so assuming Switch 2 makes the Switch 1 totally obsolete, we'd need another year+ of strong sales to rise to number one. If the Switch 1 continues to be sold after Switch 2 is released (not fully backwards compatible, Switch 1 price drop, Switch 2 is just more expensive), then less than a year or strong sales plus another couple years of long tail sales to get over the hump.
If it overtakes, I can imagine the most likely scenario to make it happen are - Switch 2 is considered unambiguous successor at $350-$400, Switch 1 price drop of only like $25-$50, basically just to clearance out the old stock, except no switch lite replacement for the first year, so the now $150-$175 switch lite continues to to rack up sales at a ridiculously apealing price. Obviously they could easily reach 1at place if they did a really agressive price drop but that doesn't seem likely for nintendo at all- a small price drop on the lite, especially if the choices are $150 Lite, $250 V2, $300 OLED, $400 Switch 2