A number of underperforming international car brands are likely to either exit the mainland Chinese market or scale down operations, as losses mount due to falling sales and shrinking market share.Carmakers delivering fewer than 1,000 units a month already faced a do-or-die situation in the world’s largest automotive market because the weak sales were not enough to cover their manufacturing and operating costs, according to analysts.Some carmakers are likely to follow Skoda, Volkswagen’s...