BARCELONA: The “ snap!... ” of a shutting phone is the nostalgic sound resonating from the giant stands of Samsung, Oppo and Huawei at the Mobile World Congress in Barcelona this week. Star of the early 2000s, the flip-phone is making a comeback, with the big names of the industry hoping the high-tech new version – the foldable smartphone – is on the verge of going mainstream.As production costs start to fall, analysts expect a tenfold increase in sales by 2026. Samsung has been the pioneer in