Intel is obfuscating how their contra-revenue is working in actual dollar terms. They are selling the Bay Trail chip somewhere in the low 10s USD. But along with those sales they are signing agreements with the following: "We're offsetting the BoM." "We're providing design assistance." "We're investing in partnerships." Etc.
Bit pointless to guess at actual $ per chip of the loss when Intel is actively hiding it. Best to just go by what shows up in the market. Based on the lowest priced Bay Trail tablets Intel is subsidizing to the low single digit US dollars, imo. IF it is costing Intel $20 per Bay Trail then ~$15 per is about right. There is also the indirect loss that doesn't show up on their balance sheet, that Bay Trail wafer could have been an actual profit making Haswell wafer.
From an Intel and Intel shareholder perspective though it's definitely worth the cost. "Fake it until you make it." Intel brand starts to get associated with phones, tablets, and soon IoT. Also less likely to make a misstep versus simply continuing internal R&D until they have the perfect product. This way they are getting direct market feedback. That's one of the things the new Intel CEO vocally criticized his company for doing in the past.
There are downsides to switching to a "ship it" design philosophy. Bay Trail graphics are mediocre for mobile with premium devices having such high pixel densities and is likely the main reason they obviously gave Asus a very sweet deal to get in their Zenfone. It will be struggling to push those pixels on that device. But Intel has its main x86 line to keep the "we're the best" marketing going. I don't think they are in any immediate risk of changing public perception of their brand.