But EU citizens working in the UK must apply for pre-settled status by the 30 June 2021. But who know what will happen by the end of 2020. A FTA by the UK-EU or US or an out right no deal scenario are possible outcomes from the process which could change this situation for EU citizens in the UK.
I just want to point out that this also applies to EU citizens who already have a certificate for permanent residence. That's right - if you went through the painstaking and expensive process of applying for a document on which the UK government states that you have the right to live and work in the UK indefinitely... that document is now worth nothing and you have to apply for "settled status" just like anyone who doesn't have that certificate.