It is worth being clear rPi doesn't include several of those costs.. a case, power supply, packaging.. i'm not sure about shipping.. but anyway it sounds like this will be more expensive. I would still be very interested if it came close; this featuring considerably better cpu, gpu and ram.
At $25 Raspberry Pi is a joke. If it actually sees a decent amount of sales, you will be sure to see actual companies that specialise in this field competing at lower prices and better performance. Raspberry Pi has realised something that everyone in the industry knows: computing is cheap. It will not take long for the competition to crush Raspberry Pi if there is a large enough market for what they are doing. As for now they are chasing after the tablet market and IMHO are going to do well.
Then you say that if the thing is a success then other companies that specialize in such hardware will come in and crush them. That's highly possible but I thought you labeled it as a joke? If that situation happens I would call them leaders in the industry as the "highly successful" companies needed someone to show them the way.
At some point, one will be able to buy a RaspPi for $25 plus shipping that requires power and a display; you're ready to go. Where's the comparable product using the A10 and how much is it?
The 15 USD however looks like the BOM cost (for 100k), so the RhombusTech device will be sold for a higher price, probably close to 30 USD.