When person establishing a Trust (soemtimes called a "Settlor") does not take the steps necessary to fund the Trust, in most instances a probate will be necessary in order to allow the transfer or liquidation of those assets. This would apply to most assets which are titled only in the Settlor's name and which do not have a beneficiary or a POD designation.
Many times clients who have a Living Trust ask whether they also should also have a Last Will & Testament. After all, doesn't the Trust do essentially everything without needing the Will? Most experienced estate planning lawyers would agree that the answer is a resounding "yes." Even though you have a Trust, you should still have a Will--a special kind of Will often referred to as a "Pour-Over Will."