As the HDB is under a sole owner (your father)’s name. Without a Will, HDB will distribute in accordance to the ISA rule or Syariah law (for Muslims). Your family will need to appoint someone (one of the siblings) as Estate Administrator and distribute the estate accordingly. The Estate administer may appoint an estate agent to sell of the housing and distribute the proceeds after the sale. HDB will not take back the housing by force. You will be given about 12 months to settle it.
With a Will, your dad can indicate how his HDB can be handled. HDB rules will still apply. E.g. for children who already own another HDB or property may need to dispose of their other property if they plan to inherit your dad’s HDB. You can find out more here.
The other way is to have your dad indicate you or your other sibling as joint-owner. In that case, one of you will be able to take over the HDB.