Well yet again, I was totally wrong: 10m did open to the USA this afternoon and quite early too! AE7YQ (8533km) was the first to spot my 500mW WSPR at 1534z. Since then, WB2TQE (7097km) has spotted me a few times too.
UPDATE 1948z: WB2TQE (7097km) was currently the last USA station to spot me on 1806z. So far today just him and AE7YQ have spotted me in the USA. I suspect there will be no further USA posts today.