Not techie at all so forgive me, but I thought this made sense and seemed like relatively low hanging fruit.
This guy just created an open source bitcoin payment gateway.http://straight.romansnitko.com/
Why not tie into this the ability for a merchant to Automagically and instantly sell their btc for bitUSD, thus taking away any currency risk.
It would do the job of bitpay and coinbase without giving up privacy. The challenge as always is to find the next guy (employer/supplier) to accept payment in bitUSD, but it seems like an important part of the process.
The press and discussion around Decentralized bitpay would be awesome.