Or maybe it is a feature ...
Correct.
If they don't get back into circulation, we will be using pico-pico-pico-pico-pico-pico BTC soon.
Please explain what you mean by "soon". There are still over 9 million bitcoins that haven't even been mined yet. New bitcoins (or fractions of bitcoins) will continue to come into existence through the mining process for another 120 years or so.