I was there for about 12 months in 2019-2020, and more recently for three months in 2022. Here is my take.
Blue dollar is still the way for foreign tourist to obtain peso. There are several options to exchange at or near the street value. Very recently the government started allowing all transactions w/ a foreign credit card to use an exchange rate very near the street blue rate. And you can also wire yourself funds to any Western Union at a rate very near the street blue rate. I have not used it, but Xoom (owned by PayPal) offers similar rate to Western Union. All these are better, simpler options than walking around listening for "Cambio!" and having to exchange cash in public in my opinion. I wish the credit card exchange rate had been in place on our last visit because I was always uncomfortable w/ the large amounts of cash (peso) I had to carry around. Large in physical size, not just amount. There are not enough large-denomination bills - a real problem w/ such high inflation, so you end up with huge piles of paper currency in lower-denomination bills. But now I would pay with credit card when possible, reducing need for physical currency.

All that said - with the new president, everything is in flux, and who knows what way it will go. During his campaign, he promised to dollarise the country and eliminate the central bank, but has given mixed signals on those goals since being elected. I would keep an eye on the Buenos Aires Times, and english language newspaper, to keep abreast of what is going on there, because I'm sure there will be significant changes coming to Argentina in the coming year.

https://www.batimes.com.ar/

I think more of it is paved, but it is no where near all paved. Worst stretch (especially if you are on a motor cycle) is (still) the section south of Gobernador Gregories, to Tres Lagos. My wife and I detoured around that in 2019, by taking 27 out of Gobernador Gregories, to 288 into Tres Lagos. Longer, still dirt (288) but much better road. We didn't ride on 70 south of Mendoza (we crossed to Chile and went south from there), but I heard that there are some dirt sections on 40 between there and the seven lakes region.

No changes, yes the same.

Do it! We are planning to return in 2024.

I think it is about the same at Machu Picchu. We did hire a guide (2019), and I think officially it is required, but some people claim it isn't enforced. IDK. But it was for me a contradiction - totally touristy (which normally I'd avoid) and totally epic and worth it at the same time. As you know since you've been there. Maybe someone else has more recent info.

Tourism industry, all over South America, took a bad hit during COVID. All land, air and sea borders were closed for almost two years, and when we were back last year, we entered Bolivia the first week the border opened, after two years! Many restaurants and hotels that showed up on Google Maps were in fact closed. Everywhere we went, people were falling over themselves to make us comfortable. In Uyuni, we were a spectacle - and one business owner told us "For us to see you here, foreign tourists, after these two years of struggle, it is a sign of hope - you are a sign that things will be getting better." Wow - it was strange experience, humbling. We left Buenos Aires in March 2020 due to COVID, just barely made it out before the country shut down, and on our return in 2022 one thing we noticed was a marked increase in homeless people living in the streets, which was rare to see before. Poverty rate has climbed across the continent.

Other changes are politics: Ecuador, Colombia and especially Peru have recently had a lot of political turmoil. Which is the norm in general I guess, but keep an eye on the news. We had to change our plans in 2022 due to the total shutdown of Peru - we were in Bolivia and planning to head north to Colombia to ship out from there. But it was impossible to get through Peru - country was totally shut down for something like a month due to blockades. We had to get home, so we changed plans, returned south, and shipped out of Buenos Aires. That's just part of the journey on such travels.

Development

Is Ruta 40 now fully paved?

Worst stretch (especially if you are on a motor cycle) is (still) the section south of Gobernador Gregories, to Tres Lagos

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This part is called "los 72 malditos". 72 km
I rode it one year ago. I don't understand why all this...
It was all lot of stones . And windy. But not that bad.

Pablo
https://www.youtube.com/watch?v=vkVf...gGlCC&index=68

The most Northly part
Cafayate to La Quiaca is all gravel.
The part around Abra del Acay is "malo. Muy Mal !!"
https://youtu.be/m1gVJ-CcTVE?si=rjMU0WULlflCm5aW



In South there is quit a lot fo gravel beteeen Rio Gallleno ttowars Chile that is ripio

We were last in Argentina at the end of 2021 for 6 weeks, previously there many times since 1989. Haven't been to Bolivia or Chile for a while. Last in Perú 2018.

The situation in Argentina is essentially the same as when you were last there - peso not floating so still an official reate and a street rate. The new official rate is now not far from the street rate however until/unless the peso is permitted to float the gap will widen again. The new president promises to “dollarise” however the country has now dollares and no-one is going to lend funds so a miracle is required to achieve this. The foreign credit card rate is not far from the street rate (to the benefit of wealthy Argentines with foreign bank accounts), so using credit cards makes sense.

Ruta 40, as others have noted there are still unpaved sections - we drove the section from Bardas Blancas to Malargüe in 2021 and it was OK. The famed section south of Gabernador Gregores wasn't bad when we drove it some years ago.

The Salar/Lagunas routes in Bolivia were OK when we drove them some while ago. Some deep gravel/sand but OK.

Global warming - you wouldn't notice in Patagonia (yet). The snowline is receding in the Andes, unfortunately.

Tourism hasn't changed that much in my opinion. Post-pandemic there’s still a negative impact in terms of income for locals, many businesses have gone bust.. Prices have increased, as is the case everywhere.

Machu Picchu - I understand that the Peruvian government recommends joining a guided tour but that you can enter on your own. The first time I was there it was required to have a ticket to go to Huayna Picchu but I could choose when to enter within two timed windows and entry to Monte Machu Picchu was free at any time during opening hours. Now you need tickets for both and there’s tighter control on entry to both.