Simple math. Nintendo can only cross the 50% of total consoles sold if they take greater than 50% market share from today forward (i.e. outsell PS4, Xbone, and Vita). Otherwise their market share of historical sales will shrink. So no, they won't cross 50%.
Theoretically, if Switch got off to an amazing start, and 3DS has a solid 201u, they could hit 50% for a short period, maybe around 1 year after release. This would require amazing sales though, and poor sales of most of their competition. So, I basically agree that it ain't gonna happen.
A year like 2007 or 2008 would do it.
2007 - 46m (N) 20m (S) 8m (MS)
2008 - 53m (N) 24m (S) 11m (MS)
The competition can still do good numbers, Nintendo has to do better.