House in trust /step up in basis

Spouses usually title their house in their revocable trust if they have one. When they die, do the heirs still get a step up in basis if the house remains in trust because the heirs need or want to use the house as their residence? When the heirs die, will the remainder beneficiaries  get a new step up in basis for the value at the original heirs date of death? If not is there a way to get a step up in basis while keeping the house in the trust. House can't be distributed to original beneficiary since he is incapable of handling financial affairs.