Switch's software won't come dangerously close to PS2's total.  It will shoot right past it easily.  Software can keep selling for years even after hardware sales have died out.

Where do you think it'll finish in sales and rank?

Seriously i cannot see Switch SW <1.6 billion. I even smell Sony "announcing" 2 billion Softwaresales because they are even harder to track despite the fact they did not have digital sales...

Switch will rank #1 in total software sales.  I'd feel better giving an estimate after I get some information from Nintendo first.  (Most of this will probably be unveiled in the next Switch Direct or maybe April 2.)  Info like:

What is Switch's software lineup this year (again should be answered by next Direct)?
Will Pokemon Legends Z-A be on Switch 1, Switch 2, or cross gen?
What models, price points and bundles will be available for Switch 1 after Switch 2's release?

After I know these things I can give you a decent estimate.  What is your estimate for lifetime software sales?

Switch 2 will also benefit from Microsoft now porting all their games.
Switch got a few games from them like Ori 1/2, Pentiment, and Grounded, but Switch 2 will likely get just about everything that will run on it.

The Suoer Switch 2 will perform better with it's 3rd party games, both in real time and offerings since it won't be a matter of proving itself to publishers since Nintendo already demonstrated the viability of the market.

Can't say it will get everything though but I'm expecting less of the harsh downgrade we get even on some AA projects.

It's gonna be a good time to play games 👌

My guesstimate is 1.65-1.9 billion depending on how the transition to Switch 2 goes (prices, crossgen period, etc) and indie support.

PS4's last known figure is "at least 15.77 billion" as of nearly 4 years (15 quarters) ago. Playstation software sold over a billion copies across PS4 and PS5 since. I'd estimate PS4's current software to be about 2 billion (which puts PS5 at about 620 million). So for Switch to rank 1, it has to sell at least 2 billion and maybe quite a bit more.

The problem here is that Nintendo is heavily reliant on first party software, so if most of Switch 2's early Nintendo games are exclusive, Switch 1's software should decline much faster than PS4's which saw a long cross-generational period.

Bold:  I'm assuming you mean 1.577 billion.

I didn't realize PS4 software sales have gotten so big, probably because they haven't updated the figure in so long.  It makes sense though.  One reason why we didn't learn PS2 hardware totals until recently is because PS3 was selling poorly for several years.  Sony bundled PS3 & PS2 hardware figures together when they reported them to mask how badly the PS3 was doing.  Now that time has passed, and people don't care as much about PS3 hardware total, they start to reveal how much the PS2 sold.  The same thing is going on with PS5 & PS4 software.  PS4 software is selling well, but PS5 software is selling poorly, so they are bundled together.

I think you just telegraphed Sony's next anti-Switch marketing move.  Once the Switch passes the PS2's hardware total, Sony will reveal the PS4's true software total just to try to rain on Switch's parade again.

No I meant 157.7 billion :P

Pretty sure they did the same thing and combined PS3 and PS4 software sales for the first two or so years of the PS4 generation.

Combining software lasted longer this generation, because unlike PS3, PS4 software remained very strong. 620 million PS5 software sold in just over 4 years isn't at all poor all things considered lol. Remember, F2P and Playstation+ downloads aren't factored in (both a lot bigger now than they were during early to mid PS4 days). How much Switch software was sold by its 5th year with a larger install base?

It'll be similar to what we have now, except devs will be on board day one this time. And a few franchises that skipped out the first time will probably make their way over. I feel like people overhype how much support the Switch 2 is going to have. This this is still going to be considerably less powerful than the PS5 and Xbox Series, so there's still going to be some games that skip it.