tl;dr The original reason I wrote the initial email is no longer relevant due to a retraction. But the timeline might still be moved up for a completely different reason.
Some more recent developments.
There are two main experimental approaches to topological quantum computing: one based on Majorana zero modes on nanowires, and the other based on non-abelian anyons in fractional quantum Hall liquids.
The Majorana approach has long been the more promising one. Kouwenhoven's group (which works closely with Microsoft) at Delft has published a lot of the biggest progress in this direction over the last decade, but it has been very slow, as the nanowire growth technique is extremely difficult, and detecting Majoranas unambiguously is also very challenging. In 2018, his group claimed to finally have unambiguous evidence of Majoranas, but a couple weeks ago they retracted the paper:https://www.wired.com/story/microsoft-win-quantum-computing-error/?utm_brand=wired&utm_medium=social&mbid=social_facebook&utm_social-type=owned&utm_source=facebookhttps://arxiv.org/abs/2101.11456
This is a big setback. IIRC, Kouwenhoven's group thought they had evidence of Majoranas as early as 2013 (maybe even before then), so it's difficult to say how long this could take to work out. At the very least, there is now less of a reason to believe that this approach will be fruitful in the near future. The original announcement about the Gooseberry control chip is still a big deal for other non-topological architectures, but the reason I felt it important to write the original email was specifically because of its potential application to this Majorana approach, and that only a few thousand Majorana qubits would be necessary to put many ordinary cryptography methods in danger.
The other main approach, with fractional quantum Hall liquids, hit a major milestone last year. Namely, the first unambiguous evidence of (abelian) anyons was discovered: https://arxiv.org/abs/2006.14115
This is not exactly what is needed for this case - something even more exotic - non-abelian anyons - are needed. But the technique utilized in this paper was designed to work for those too - they just started with the easiest case.
Like Majoranas, these are also extremely difficult to detect. Unlike the Majorana zero mode case (where the difficulty in their detection is closely related to the fact that they have zero energy, so many effects can obscure them), the signature here is unmistakable - there is nothing else known that could create the data. However, the Gooseberry chip is not the right kind of device to control these sorts of exotic quasiparticles. For both Majoranas and anyons, the idea is to "braid" their worldlines in spacetime to perform quantum computation. For Majoranas, the simplest way this is done is by creating T-junctures with the nanowires, and moving Majoranas past one another at the T-junctures. But for anyons in fractional quantum Hall liquids, the substrate in which they appear is necessarily disordered, and so anyons are essentially trapped wherever they are spawned (due to a phenomenon called Anderson localization).
The proposed method to get around this is a technique called measure-based topological quantum computation, which (now this starts sounds like science fiction) works by using quantum teleportation on the anyons in the fractional quantum Hall liquid to do something like braiding them. This requires a totally different sort of electronics than the Gooseberry chip. I don't actually know whether anybody has even started on this part of the problem yet. In any case, I'd be surprised if there is a topological qubit of this sort before 2025, or even 2030.
Despite this - there was recently an article published by Bloomberg, saying that a quantum computing company Terra Quantum AG claimed to have discovered that quantum annealers (much simpler machines than universal quantum computers that only perform one algorithm, primarily build by D-Wave) are able to break encryption methods they previously were thought to be unable to. https://www.bloomberg.com/news/articles/2021-02-07/a-swiss-company-says-it-found-weakness-that-imperils-encryption?srnd=technology-vp
At this moment, as far as I have been able to tell, they have not published a paper saying how this can be. It's rather unusual to go to a media outlet about this before a paper is available. So I am quite skeptical. On the other hand - it is only strongly suspected by experts that modern cryptography methods are not broken by quantum annealers, but there has never been a proof of that. So it's not impossible. It's worth paying attention once they actually have a paper - and if it holds up to scrutiny, it's basically Red Alert, because quantum annealers are much easier to build than universal quantum computers. But the circumstances are very odd, so I would still bet against it if I were a gambler. For now, there's nothing to go off of.