Discussion of sync engines typically goes hand in hand with local-first software. But it seems to be limited to use cases when the amount of data is on the smaller side. For example, can anyone imagine how there might be a local-first version of a recommendation algorithm (I'm thinking something TikTok-esque)? This would be a case where the determination of the recommendation relies on a large amount of data.
Or think about any kind of large-ish scale enterprise SaaS. One of the clients I'm working with currently sells a Transportation Management Software system (think logistics, truck loads, etc). There are very small portions of the app that I can imagine relying on a sync engine, but being able to search over hundreds of thousands of truck loads, their contents, drivers, etc seems like it would be infeasible to do via a sync engine.
I mention this because it seems that sync engines get a lot of hype and interest these days, but they apply to a relatively small subset of applications. Which may still be a lot, but it's a bit much to say they're the future (I'm inferring "of application development"--which is what I'm getting from this article).