Maybe? I've previously said I think Switch software will end closer to 2 billion than 1 billion, which based on the ranking in the first post may be nearly the same thing. At least, Sony's choice to stop bragging about PS4 software sales on their own may keep us from knowing for sure if PS4 remains in the lead.
In my search for Patterns, I've previously looked at other recent Nintendo systems and how software trailed off after it hit a peak. Like, DS software peaked when it was at 533m, but it eventually reached 949m so it gained 78% more on the way down. For 3DS, it was +138%. For Wii, +161%. For Wii U, just +16%. Not very consistent. But Switch hit its software peak just last year, when it was hitting 918m total. So it needs +63% to join the 1.5 billion club, less than all of those except for the assassinated Wii U.
Separately: Since backwards compatibility should suck less than it did for DS on 3DS or Wii on Wii U, I think Switch software will drop off more slowly than those systems' software did.