No EU citizen currently in the UK lawfully will be asked to leave at the point the UK leaves the EU. We want you to stay. Second, any EU citizen in the UK with five years continuous residence, at a specified cut off date will be granted settled status. They will be treated as if they were UK citizens for healthcare, education, benefits, and pensions.
While any EU citizens with less than five years residence who have arrived before the specified cutoff date will be able to stay until they have the five years residence to apply for UK settled status. Third, the specified cutoff date would be the subject of discussions, but it'll be no earlier than the date we triggered Article 50 and no later than the date we leave the EU.