In an interview with Toms Hardware MSI's CEO Charles Chiang stated that upcoming X570 motherboards are not going to be cheap.  Certain technologies used in the motherboards are rather expensive.

It is even mentioned that MSI's X570 motherboards are unlikely to be more affordable than Intel's Z390 boards as production costs are higher. He says that PCIE 4.0, which consumes more power and makes the design more complicated, among things that is a factor in added costs. 

"Lots of people ask me, what do you think about today's AMD? I say today's AMD is completely different company compared to two, three, five years ago," Chiang said. "They have nice technology and they are there to put the higher spec with the reasonable pricing. But right now they say, "Hey Charles, lets push to marketing to the higher [end]. So let's sell higher-pricing motherboards, higher-spec motherboards, and let's see what will happen in the market. So I don't think that AMD is the company that wants to sell low cost here, low cost there."

Chiang noted that X470 motherboards will remain in the market and could serve as a proper value alternative.

Updated June 19th: the first motherboards started listing, they indeed start at the 200 EUR/USD marker. Please note, the prices listed are Austria EUR prices, often higher than regular EU based prices.