Really? I was using Mobike as a foreigner in China for a while and I don't recall them asking for a 身份证 or anything (did they ask for my passport number? I don't think they did), plus they have a pretty well-translated app and already operate in other English speaking markets including the USA and Singapore. For Mobike and Ofo they should be flush with enough money that the likelihood of them shutting down all of a sudden is relatively unlikely, but just in case when I left China I did get my deposit refunded fine.