Thanks for the link, but while I am searching now even on bitcointalk there are many members said Kucoin ask for KYC compliance even if their limit is below the level what they mentioned for non verified customers and also some account under froze until they complete KYC so with any centralized exchange regarding KYC or no KYCed account the user should be asked to verify their Identity at anytime which is also mentioned in their ToS so yes there is no guarantee that someone can withdraw as non verified user forever.