These people at this reference, interpret the final grail scene the same way I do:
The Grail is lost forever. (bold mine)
Elsa grabs it and runs off, but when she crosses a forbidden area, the
temple collapses, and Elsa and the Grail are lost forever.
The Wikia site for Indiania Jones says this about the Holy Grail(bold mine):
Indiana nearly tumbled into the abyss himself, but was caught by his
father. Indiana, like Elsa, tried to reach the cup, but was persuaded
by Henry to let it go.
As a result, the Grail was ultimately lost following the events of the
adventure, but the experience gave both Indiana and his father the
chance to rekindle their rocky relationship.
Also that page mentions:
Years later, the elder Jones remarked on the elusive, indefinite
nature of the Grail, commenting that the cup discovered by the
father-son team was simply "a Grail. But many of the oldest Grail
texts, written by the most ancient seers, refer to the Grail as an
elixir, as a bread, a powder, gold, or a stone."