3. If Bitcoin does not succeed as a global payment solution, how likely is it to still be a store of value?
The mainstream global payment you mean here is not necessary before Bitcoin will be a store of value, but it will help in its adoption. What that matters most is for people to see the real fact about Bitcoin and buy it. Know that Bitcoin is not only a payment means, it is also an asset on its own with its limited supply which makes it deflationary and appreciative in value as it is adopted.
3. If Bitcoin does not succeed as a global payment solution, how likely is it to still be a store of value?
I do think about this at times, like if the whole world just go against Bitcoin, this may lead to even mining industry to collapse, forcing all miners not to mine again, ASICs manufacting companies can be mandated no to produce the mining machines again, and the likes. This can lead to crypto extinction generally, but this will significantly affect people negatively, I believe the governments will not want that.
Some people do not like cryptocurrencies, some people really like it, this can not make crypto ban possible. We have seen in some countries as opposition party succeeded for the presidential seat and crypto that was banned were legalized again.
Like in Nigeria, the opposition party leader that contested as the president even
supported cryptocurrencies. If he has been the president by now, I believe cryptocurrencies wouldn't have been banned by the CBN. This is just the politics that is going on in the world, people are not the same, countries are not the same, the reason Bitcoin and other cryptocurrencies can not be banned. So, there won't be anything like governments coordinating together to ban cryptocurrencies. As some will ban, some will accept, and countries that even support Bitcoin are far more than those than ban it.
Yes, there are ways to exchange bitcoin without centralized exchange.
This is even the best way to go if seeking for privacy, there are decentralized platforms that people do meet to exchange cryptocurrencies like Bsiq, Hodlhold and Localcryptos. There are even platforms like Bitcointalk we can easily trade cryptocurrencies, people that are into crypto for long even know more people they can directly trade crypto with without even using any platform.