Even if some places accept Bitcoin, the price is still quoted in dollars?
It depends on what you prefer, there are some local exchanges that Bitcoin is paired with local fiat. Like El Salvador that just recently accepted Bitcoin as a legal tender, Bitcoin will be paired with the El Salvador fiat currency. But most people like it paired with US dollar, it is just preference, while also dollar is the most recognized currency which makes it common and default.
Bitcoin's value per say is in US dollars, a fiat currency subject to inflation.
1 Bitcoin is 1 Bitcoin, but people are mostly using fiat, and Bitcoin price is paired with fiat to make people know its worth to fiat.
If we remove the value based on the dollar, then is the price of Bitcoin just based on supply and demand?
Yes. Even the increasing demand has been the main reason Bitcoin is valuating and increasing in price and marketcap, while almost all Bitcoin are mined and the supply into circulation is reducing, the reducing supply into circulation is also helping in its valuation because if more supply is introduced into circulation, it will affect its price by making I not to valuate the extent it supposed to be. People even not much talking about the fiat inflation that much valuate Bitcoin if compared to fiat, but it is also important as it is also part of the factor.
I also hear people like Cathie Woods and analysts at JP Morgan say Bitcoin will reach $500k or $140k respectively. I understand for stocks you can look at financial statements and make valuation models to calculate target prices, but for Bitcoin, is the value based on the scalability of network?
It can also be calculated. Also nothing scalability has to do with the calculation, scalability deals with transaction speed.