There’s no way to guarantee absolutely, but you could wait to announce until you got lucky with a couple consecutive blocks if you had a lot of hashpower (pool

There’s no way to guarantee absolutely, but you could wait to announce until you got lucky with a couple consecutive blocks if you had a lot of hashpower (pool operators). It would be an expensive endeavor since it involves throwing away solved blocks, but could of course package many QC safe(r) transactions so probably a profitable service in a QC compromised era.