Short answer. Yes. Article 878 says that a disposition with a suspensive term does not stop the instituted heir from acquiring his right and transmitting it to his own heirs even before the term arrives. The future date delays delivery, not the right itself, so your heirs take your place.
What the law says
A disposition with a suspensive term does not prevent the instituted heir from acquiring his rights and transmitting them to his heirs even before the arrival of the term.
Civil Code, Article 878 — Dispositions With a Suspensive Term. Read the full provision →
What Article 878 provides
Article 878 provides that a disposition with a suspensive term does not prevent the instituted heir from acquiring his rights and transmitting them to his heirs even before the arrival of the term. A suspensive term is a future date or event that is certain to come — 'five years after my death', or 'when my youngest turns twenty-one'. It postpones when the heir may actually demand the property. What Article 878 makes clear is that it does not postpone the heir's ownership of the right. That vests at the testator's death; only its enjoyment is deferred.
The crucial difference between a term and a condition
Everything here turns on the distinction between a term and a condition. A term is certain — it will arrive, only the date may be open. A condition is uncertain — it may or may not happen. With a term, the right is already the heir's from the death; he simply waits to enjoy it. With a suspensive condition, by contrast, the right does not vest until the uncertain event occurs, and an heir who dies before it transmits nothing. So whether your heirs step into your place depends on reading the will's future date as a term, which is certain, rather than as a condition, which is not.
Why the right passes to your heirs
Because a term only delays enjoyment, the heir's right is a present asset from the moment the testator dies. It forms part of his own estate. If he dies before the term arrives, that right does not lapse or return to the other heirs; it passes to his own heirs along with everything else he owned, and they wait out the remainder of the term in his place. When the date finally comes, they receive what he would have received. The testator's chosen delay runs its course, but the identity of who ultimately benefits follows the ordinary rules of succession from the first heir.
Reading your own situation
If a will gives you something at a future date, the key question is whether that date is a term or a condition, because only a condition would put your heirs at risk. Look at whether the event is bound to happen — a fixed period, a birthday, a date certain — which points to a term, or whether it might never occur, which points to a condition. Where it is a term, your interest is already yours to pass on, and worth recording as part of your own estate planning. Where the wording is ambiguous between the two, that reading is the whole question and should be resolved carefully.