Help to Buy ISAs stop on 30 November 2019. There can be no new H2B ISAs after this date.
Existing H2B ISAs taken out before this date can continue.
You can still invest as normal and still get 25% bonus.
You can still withdraw early, as normal, (with penalties/loss of bonus).
First Time Buyers must use/cash in their Help to Buy ISA and be buying a property by 2030 to still receive their 25% government bonus.
After 2030, the bonus is lost and Help to Buy ISAs becomes normal ISAs.