One might say that Crew Dragon's days are counted already.
Even SpaceX' Gwynne Shotwell (she is SpaceX' long-time COO, in case you do not know her yet) is hoping that SpaceX will fly people on Starship in maybe 3-4 years and she is way more grounded than Mr. Musk.
They plan to achieve this unreasonable sounding feat by producing large numbers of Starships and launching them very often to accumulate massive experience with the craft in very short time in parallel basically.
I wouldn’t say she is that much more grounded: she has also said they are planning on passenger New York<->Shanghai rocket trips for a price between an economy and business class plane ticket by 2028:
So that's longer than from Alan Shepard's flight to Moon landing. And the task - with all peculiarities - still seems simpler.
I don't think this points to the "ungroundness" of Shotwell. Similar projects were discussed and BOTEd for quite some time. The whole suborbital tourism thing is practically rather similar technology, and we're a couple of decades in the implementation time for that.
It is hard to emphasize how much harder that last X% of reliability is to allow something like this for flights of hundreds of civilians. We’re not talking space tourism but a utilitarian service for business travelers and stuff.
Hey don’t even have a settled design and have made radical design changes recently.
SpaceX commercial crew program began in 2010 and is only just coming to fruition.
But principles are long since known, and prototypes are coming more and more often. Delta-Cliper, Space Ship One, New Shepard, unmanned Dragons, first stages of F-9, aerodynamic tests in wind tunnels - all of them contribute, to various degrees, to the technologies needed.
That doesn't seem like a crazy estimate. It's not conservative, but seems doable.
The very first SpaceX launch was in 2008. Since then they have developed and iterated on reliable, reusable space travel. Its plausible that they can adopt that technology to a commercial platform in 8 years.
What's great though is that all the technology, systems, tooling, procedures, experience, etc.. that has been developed for Dragon 2 will roll right into Starship. It's a huge head start.
Even SpaceX' Gwynne Shotwell (she is SpaceX' long-time COO, in case you do not know her yet) is hoping that SpaceX will fly people on Starship in maybe 3-4 years and she is way more grounded than Mr. Musk. They plan to achieve this unreasonable sounding feat by producing large numbers of Starships and launching them very often to accumulate massive experience with the craft in very short time in parallel basically.