Surely someone has proposed the existence of a civilization forming from <=iron and making the heavier elements themselves? Seems far fetched but you have quite a bit of time to play with there.
So here's a fun experiment for you. Look at a periodic table and start with Cobalt (the first element after Iron) and look at what its uses are. Wikipedia is fine. And then ask if there are alternatives for that metal. In some cases we won't know but in other cases, the situation would be dire.
The first few include Nickel, Copper and Zinc. Think of all those alloys and direct uses, particularly copper as an electrical conductor. Or all the rare earths for magnets and semiconductors. Or gold or lead even.
Then there's Iodine, which is actually essential for human life. Zinc, selenium and others are used too, possibly others.
The scarier question is what happens when the universe runs out of hydrogen in vast quantities? It will only be around for stars to burn for so long. Most are in the billions of years. A handful are in the trillions. But eventually they will run out too.
Obviously this doesn't answer your question, but there are scifi stories about alien civilizations that arise on planets without heavy metals. Usually the plot revolves around their not getting past the stone age.
