Some folks struggle with the concept of estimation, incorrectly confusing it with blind guessing.
"Estimation (or estimating) is the process of finding an estimate, or approximation, which is a value that is usable for some purpose even if input data may be incomplete, uncertain, or unstable. The value is nonetheless usable because it is derived from the best information available."
Due to the many unknown variables it is difficult to apply much precision in the delivery estimate, however it does not mean nothing can be "guesstimated."
Past performance of similar projects is a common technique used by PMs to develop software estimates, and they apply well here.
One can look at SC, CU, CF, AoC, Pantheon and a host of others to compare the "progress" (or lack thereof) of COE against those other efforts.
Based on this data alone it is reasonable to assume COE has a very long way to go, and early dates such as 2019 or 2020 are very much the overly optimistic or long shot views.
A middle of the road estimate for full launch is probably 2025 or so, assuming the funding holds out that long.