It is possible but be completely pointless since each participantt would be getting a few satoshis which would be worthless unless the price goes up a lot.
Unless they were mining for spending on microtransactions. But Bitcoin's PoW hash is too favorable to ASICs versus CPUs to make this viable as you say only a few satoshis in relative hashrate.
It's not completely pointless at all! If sufficiently many users are willing to run a microminer at a small monetary loss, then it becomes practically impossible to run a commercial mining farm. I think we're quite far away from that scenario, but it's a theoretical possibility. I hope that eventually a hundred million people will care enough about decentralisation, and in that case it might happen.
You astutely describe my design for eliminating commercial mining. But I don't rely on them caring about decentralization.