This is a really good breakdown. I can't read our investors's minds, but I'm pretty sure this would be a worst case scenario for them. It's certainly not why we're doing Rethink -- if we thought it would be a #5 company in the space, we'd pack up and do something else (life's too short).
The NoSQL market is reminiscent of "horseless carriages" -- as long as you define a technology by an absence of something, you know you're early in the game. Databases are a fundamental part of the technology stack, and they tend to easily stick around for 20-30 years. We think we can build a long-term open source company that will stick around for that long (incidentally, that's why we take conventions in ReQL so seriously -- we imagine millions of programmers fifteen years from now cursing at us for a stupid naming convention).
It's not hard to imagine groundbreaking features in NoSQL products that nobody is shipping. That's why RethinkDB exists, and we think we won't be a niche product for long.