okay ... i'm seeing 2 days of stability ... indexed pages coming back and new sites are being indexed. Lets hope it holds
I don't know why they would want to drop pages from their index. This is because if they want to stay the best then they also have to be the largest meaning more pages in their index than the other search engines.
I guess size is in the eye of the beholder. It's so easy for webmasters to create tens of thousands of pages per day to their sites now days. Most of these pages will be consider BS to Google. However, they still need to find origional content or you're right they will have big problems on their hands, eventually! I believe one of the biggest problems for Google and other SE's started when folks could buy and host domains for less than $10 per month. When this happened millions of people could create hundreds of millions of pages to try and game their system. Sadly, their efforts to stop this kind of activity hurts the single website owners, badly, who are just trying to build a good website and add quality content on a regular basis.