For most research areas I'd agree, "20 years" = "who knows". But for cryptography people using it should keep looking carefully at how long something they encry

For most research areas I'd agree, "20 years" = "who knows". But for cryptography people using it should keep looking carefully at how long something they encrypted will remain safe. People may be betting a lot on the assumption that something stays secret for at least 50 years. Therefore any significant shift in those probabilities is newsworthy, in my opinion.