Conway's law would still apply in a company where the org chart is changing. Obviously old systems don't disappear in a reorg, but new ones will reflect the communication structures at the time that they were built.

In companies that go through frequent reorgs, you'll often see a lot of "scar tissue," where you can tell that one set of services date back to a particular epoch. For example, these services are from a different time when the company tried to enter a new market, and here's a bunch of messy microservices from when the company added a bunch of developers after the Series C and the engineering processes failed to keep up. And along the way, you'll see a bunch of half-finished migrations that require both the old and new systems to be maintained simultaneously.

In your example, if that org is adapted to frequently shifting team boundaries with some central top-down architectural authority (CTO, architect, committee, whatever), then Conway's law would predict exactly the kind of modular architecture with a "shared design approach" that you describe.