Well for 1 you will see millions of made for Yahoo sites pop up forsale then you have thousands of other reasons that I really dont need nor want to get into.
It will probly go to countrys like - UK, Australia and Canada before it even goes near India, as these countries have advertisers that would want to target the ragions. So I think its going to be a while....
I think probably we should have some stats, how many publishers out there ? Their Countries ? Advertisers ? etc.. may be the G and Y have those stats and they will decide at what country should be the next one, as said above may be it will reduce the CPC but for Yahoo it will increase their income and I believe first they'll look after their income and next others... and it will be a good competition with Google..
One of the best reasonable reason why yahoo is so cautious in expanding the scale of YPN is this --> You guys (indian) are so smart ! Some of the Indian web-masters hired a whole village to do human clicks. Some women do the clicks when they feed their babies. They even provide some tools to "make" the click looks "natural" to google. My uncle works for google and he told me that. That is stupid and causes too much troubles for Google or yahoo and it affects the future of online marketing. Some Indian publishers do a good job though. Some of my friends are Indians and they are doing a good job. No offense for good Indian publishers.