Here are my responses and I urge you to understand they are just one view (mine) in the avalanche of speculation Amazon's report created.
Yes, more and more. Some bring out e-versions at the same time as the print book is released. Others wait until a hard-cover bestseller comes out in paper-back. But still others don't e-publish at all or restrict the availability of the e-version to the USA, probably due to the rights awarded in the contract.