What if suddenly Google, yahoo, facebook, microsoft start charging for their services?

Situation will look interesting. ALL of them will have to do it SIMULTANEOUSLY in order for it  to be effective. It will look like a cartel action. There can the be MRTP type cases against them in almost every country - Yes, almost ALL countries have some similar law that deals with cartelisation.

But, there will be a distinct improvement in the quality of posts, and the corresponding fall in the quality that the average social site blogger is doing.  Posts similar to something like these will totally stop:--

1. Photo of my neighbour's dog licking my face....... 2. I went to Shimla yesterday, It was sooooo coooldie. mattrers thatmost people dont care a damn about.

Another interesting aspect will be if chaps like Toostep also charge. Then basic time-pass posts like this, including all the replies will stop. Maybe, it will be slightly more sensible and content worthy. May be worth a try.

1. Most of these chaps have other than the "free-version" for "cheap=skates" like you and me, a Corporate and Commercial version where the level of service is +++ than what we are getting here in the free version. The charges for this are relatively steep and there is a good clientèle. These have no disturbing advertisements, pop ups etc.

2. They are also getting a lot of money from the advertisements that we are forced to see.

3. Our email addresses, browsing habits etc. add food for their R&D and to the ability to send directed mails.

All told, it would be counterproductive for them to stop the same. If they plan to, and give sufficient notice, then we may have to prune down on multiple accounts, social sites etc. and bring it to the bare minimum. As a "technical" man with "expertise" in several domains, I get (both paid and free) technical  literature in various different email accounts. Looks simpler for management. Now may be I will have to consolidate them all into one single account. Price is not too high, and service is better (yes, at times even the "free" Google mail is dead=slow), it is worth considering. 

the benefit of making them paid services is not so attractive otherwise they would have done it longago