It does not say, “Speak to the Children of Israel and say to them…”, but “Command the Children of Israel”.
In the Sifrei the rabbis point out that “command” is stronger than “speak” and it implies miyyad ul’dorot, “now and for all time”.
Building the Tabernacle was not an eternal command in that sense. In time the Tabernacle was replaced by the Temple, and though we continue to pray for the restoration of the Temple we have had nearly two thousand years in which the twin sanctuaries of the synagogue and the home have been our sacred centres.
What has never been in limbo has been the kindling of the lamp; the command was “to cause the lamp to burn continually”.
The word “lamp” means the Perpetual Light, the ner tamid; it also means bringing the light of the Divine into our lives and our world.