While Prometheus's built-in local storage is not distributed, we are in the process of implementing generic interfaces to allow Prometheus to talk to decoupled distributed, horizontally scalable, durable, remote storage (or even other non-storage systems like queues etc.). There will be several implementations sitting behind this interface in the end (see already Vulcan from DO and Frankenstein from Weaveworks, both experimental right now), depending on what you'd rather run and what fits your use case best.
Most importantly, Prometheus will never decide to exclude a feature for commercial reasons. As it's a 100% open-source and independent project not controlled by any single company, we don't have those kinds of incentives. We just want to build the best monitoring system. Note that we still say "no" to a lot of features, but that's only for technical reasons, to avoid bloat, or to keep the project maintainable.
Most importantly, Prometheus will never decide to exclude a feature for commercial reasons. As it's a 100% open-source and independent project not controlled by any single company, we don't have those kinds of incentives. We just want to build the best monitoring system. Note that we still say "no" to a lot of features, but that's only for technical reasons, to avoid bloat, or to keep the project maintainable.