NEW YORK — White House-led talks on the future of TikTok are coalescing around a plan for the biggest non-Chinese investors in parent company ByteDance to up their stakes and acquire the short video app's US operations, according to two sources familiar with the discussions. The plan entails spinning off a US entity for TikTok and diluting Chinese ownership in the new business to below the 20-percent threshold required by US law, rescuing the app from a looming US ban, said the sources, who asked to be kept anonymous because they were not authorized to speak on record.