financial impact of "premium" services

This is meant to be meaningful discussion of the actual benefits and maybe detriments to "premium" services.

As many have said, Blizzard is a company, and as thus, it's not for us to decide how much money they are allowed to make.

However, we are paying customers, we pay to play this great game. Now with what seems to be more and more talk of "premium" services, and with the implication from the post is that there are going to be more coming, we have to wonder where it ends.

So here's an example: Say the cost of the ability to play with RealID friends is $3 a month (not unreasonable, and I think a probable cost considering Remote AH and Guild chat), at what point does this decision end up costing Blizzard money.

If 1 in 100 pay for this service, yet 6 in 100 quit because of protest, it becomes an unprofitable venture, they lose more customers than the money they bring in.

However, the flip side is, if it was actually implemented as an ingame service (meaning free) how many customers would they gain? Would people come back and play because of this? Or maybe the potential of keeping people from quitting?