the switch should end 2023 with around 135 million units globally it would have to sell another 23 million to pass the ps2. With Switch 2 coming in 2024 that seems difficult. I would like to know users' opinions

Well, could it? Of course it could.
https://www.youtube.com/watch?v=Ysh44rPC7ew
It has two big things going against it reaching or slightly surpassing PS2.
1. Lack of price cuts. Yes, Switch Lite has been available for years as a $200 USD option. But it is a Switch that cannot Switch and can still get JoyCon drift which is even worse in a dedicated handheld. I know inflation is a thing, so PS2 selling around the end of its life for $100 USD would be more than that today, but still cheap. Even when Switch 2 releases, there is a good chance Nintendo doesn't cut Switch's price. They'll probably just include a game or two with each Switch.
2. Switch 2 is set up to be a smash hit and likely launching March 2025 or before. Nintendo has not been in this good of a spot with a home console since the NES to SNES transition and on the handheld front the GBA to DS transition. I know Switch 2 hasn't been announced yet with a codename or unveiling, but it's unlikely Nintendo will make it another Wii U.  

Probably not. 

The PS3 only sold about 6 million after 2013. According to the figures we have, PS4 was at 91 million at the end of 2018, and finished at 117ish. So, it probably sold 10 million at the absolute most after 2020, and probably a lot less. If Nintendo wanted to be aggressive about it, maybe they could do it. Drop the Switch lite to 150 or 100? That might help. But, I don't think they have much interest in doing that. I think they'd much rather you move on to the next. Sony had an interest in continuing to push the PS2, but that was a different market situation. 

Honestly, it is very up in the air. But here are some thoughts

1. NG releases in 2024.
   Switch will not surpass PS2 unless the price is lowered by $100 of each iteration.
2. NG releases in 2025
   Switch will be able to, if the NG is backwards compatible, and the Switch iterations are $100 off.
3. NG is counted as Switch sales, like how GBC sales were counted as GB sales
   Switch sales will be near 210M.
4. Switch doesn't receive drops in price. It will not surpass PS2 and will end up at 155M max.

Switch needs to sell *on average 11.5M units for 2 consecutive years  (Switch has at least 2 more decent years left until it crawls). That will be extremely difficult, especially if the NG releases sooner than later.
Nintendo stated that they will be supporting Switch to at least a minimum of March 31 2025. So we guarantee another year and 3 months of Switch hardware selling.
Nintendo has also stated that selling 15M for the year will be a challenge, but it looks like it will land at 14M (as long as Dec lands near 135M).
I think Nintendo will plan to sell 10M for the following year. So after that we will be near 148M sold as of March 31 2025. From there it will need to sell another 10.7M. Most consoles sell for 10 years, but usually Nintendo stops production of the older console 3 years after the new generation. So we could see Nintendo still producing Nintendo Switch until 2027 or 2028 (depending on a 2024 or 2025 release date).
So after March 2025 Nintendo needs to sell 10M units until 2027. That seems doable, especially if the price is reduced. But all of these dominoes have to fall in order for 159M+ units sold.

*it used to say that Switch needed to sell 11.5M units in 2 years, now that statement has been fixed to Switch needs to sell on average 11.5M units for 2 consecutive years

Seems impossible
Switch 2 releasing end of 2024 then I can only see Switch selling another 15 million
2024: 8m
2025: 4m
2026 and beyond: 2m
Switch 2 releases in 2025 then it could sell another 18-20m so still only around 155m
2024: 10m
2025: 5m
2026 and beyond: 3m
Switch 2 delay to 2026 for switch to have any chance of passing the PS2

I don't understand why they wouldn't want to lower the price of the Switch. That would seem to tap into the just about the only market they haven't been able to tap into yet (Those that are waiting for a price drop). And those people are going to need games to play on the system, which means they'd make more money.

You would rather people buy the console you're still producing content for. The person who buys a Switch now will pick it up, grab a few games they're waiting for, and then move on, assuming Nintendo doesn't go heavy on crossgen. With the Switch 2, you're continuously putting out new content, which is more likely to keep them engaged. 

They're definitely going to make more money in the long run with a Switch 2 buyer than a Switch buyer. Depending on how low you can get the Switch while still making a decent profit, how much the Switch 2 will launch at, it might make sense, but probably not. 

Could, but Id say probably wont.

PS2 has a massive *

Probably 20-30 million PS2 sales, at least, came from people simply wanting a cheaper DVD player and not even interested in games.

Anyone who buys a NS does so to play games. NS won this battle already.