It is! Taking into account that only the Schor algorithm is proven to be exponentially faster in factorising numbers and looking into current progress on using it, the threat for RSA 2048 will become real in ridiculous 2^2048 years. This can be estimated by taking three events in factorisation:

2002: factorisation of 15 [1]

2012: factorisation of 21 [2]

2022: factorisation of 35 by IBM (although the article is about number 21, but let’s give them credit) [3]

In a plot, the tendency is somewhat linear, with the factorised number increasing by one every year.

A sceptic immediately replies to this thread, saying we already have 100-1000 qubit quantum computers and are on the path to getting a million qubits in the foreseeable future. That may as well be true. The issue is that the Schoor algorithm requires that the error rate of the qubit operations scale exponentially with the number of qubits. This is why IBM only uses five qubits in [3], although they already had a hundred qubit QCs at that time. It just produces meaningless results when used with more qubits.

This is also why the line for factorisation is about to be linear. If the error rate of the qubit operations decreases by 20% every year and we have exponential progress, the usefulness of the Schor algorithm taken on a log scale would be linear.

The error correction is not a panacea either. It does not reduce errors to zero for logical qubits but rather reduces them after the error threshold is reached. It would require repeated application to get the necessary error threshold to run the Schor algorithm for a desired number, which would require an unreasonable number of qubits.

[1]: https://www.nature.com/articles/414883a

[2]: https://www.nature.com/articles/nphoton.2012.259

[3]: https://arxiv.org/pdf/2103.13855v1.pdf