Yes you can continue using Term Deposits, however the maturity of the term deposit  will be the same or less than the validity of your document proving residential status in Vietnam.

a) If you have a Term Deposit before 5th Jul, 2019, Don’t worry your term deposit will be kept until its maturity. You don’t need to submit any additional documents.

b) To open a new Term deposit from 5th Jul, 2019, you may need to submit documents issued by the Authorities to prove you are allowed to reside in Vietnam from at least 6 months.

a) The regulation states that Non Vietnamese customers, with a valid document proving residential status in Vietnam with at least 6 months will be eligible to open Term Deposit Accounts with a Term not greater than the remaining of its validity.

b) Read more about this Circular here