So what do you think would happen if they switched to a fuel-rich staged combustion cycle? (Forget reusing an ox-rich preburner setup. YOu'd probably have to rebuild the hot section after each flight... if it doesn't eat itself alive like an NK-33.
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Not that it makes much sense right now, but it sure would produce a much higher specific impulse and allow a much better performance. Also it would make the engines much lighter at the same thrust, since you could operate at five times the current chamber pressure without problems.
Please remember that a single NK-33 had a turbopump failure right now, while already almost 100 Russian rocket engines with ox-rich preburner flew successfully. That technology is not that bad at all.
And for reusability, it would already be enough if you could detach the turbopump block of a rocket engine with just a few screws and install a replacement block, while inspecting the old turbopump after a few flights. While this is already hard to achieve in terms of engineering, it could be cheaper than swapping a whole engine.
