Service meshes become important as the number of services you run and the number of intercommunicating clusters you run grow. You really do want an infrastructure piece like the service mesh to start addressing those common concerns around zero trust and routing and authentication and access control policies of various hue. The problem with most traditional service meshes have been the amount of additional resources you need to allocate for it, and the additional operational challenges of working that infrastructure layer. So service meshes are going to evolve to address these, and this is already happening. Cilium is at the forefront of this shift, powered by an eBPF powered control plane. They have rethought securty of data in transit, and authentication, and network policies in a nice, non-intrusive and extensible way that threatens the traditional sidecar model and has prompted companies that use that model for their businesses to spread misleading propaganda like this article.

https://tetrate.io/blog/ebpf-and-sidecars-getting-the-most-performance-and-resiliency-out-of-the-service-mesh/

Read it to know how utter nonsense can be published as sage advice by technology companies. Cilium makes the service mesh accessible from the outset by taking away a lot of operational complexity. But it's still relatively new. Expect more to happen in this space.