The Switch is still over 11 million away. It will take time for it to catch up and outsell the lifetime sales of the 3DS.
Yes, but launch-aligned it's a gap of ~2m now and momentum heavily favors Switch. 2020 is on track for 5m+ for Switch while the 3DS sold only ~3.15m in 2014; month 34 had a gap of ~2.5m, so most of that will be closed by the end of 2020.
Even if Switch declines in 2021, the 3DS declined as well, so a year from now is about the time when Switch will have passed the 3DS launch-aligned. It's hard to imagine that at that point anyone will doubt that Switch will take the win in lifetime sales.