@Susan: I think this is a step in the right direction to standardize. While they are at it, why not standardize even further for above 10watt supply? USB 3.0 is capable of handling much more and this will come in handy for Tablets and Laptops.
Reg your question on old chargers, no doubt they have to be reclaimed and recycled. Standardization like this will reduce eWaste.
It's very fashionable to knock the EU here in Europe, but generally I am in favour. There is a lot wrong with the EU, but to me, as a libitarian, free-marketeer, breaking down barriers is a good thing. It increases competition and so reduces prices. However...
Here, the law of unintended consequences kicks in: if Apple were to make special models for Europe with micro-USB connectors, then competition is reduced and prices will rise as sure as night follows day.
I'm all in favor of standardized chargers. I have two cameras and my son's DSI that all use non-standard connectors, which means I have to search all over the house when one of them gets low. It would be nice if I could just use a standard USB charger.
On the other hand, the problem with bureaucratic rules is that they can stifle innovation. What about the soon to come out USB 3.1, which is faster, can handle higher charging current, and is reversable, like Apple's Lightning connector? Will this be illegal in Europe?
Standardizing on a mechanical USB connector is only step 1. Today, you can connect a Samsung phone into a USB connector, an LGE phone into the same USB connector, or a Nokia phone into the same USB connector. All phones will fit into the charger, but all will charge differently.
This is because the electrical communication between the USB host charger and the USB device is not standardized.
Today, Samsung offers their own propietary communication signals, Qualcomm quickcharge 2.0 is now available with yet another set of communicaiton signals. BC1.2 is also a spec which tries to dictate what the communication signals will look like. USB-PD is also trying to become a standard which allows up to 100W to be negotiated through the USB connector.
EU needs to look beyond just the mechanical connector (which btw they have chosen a horrible one because it is an easy connector to break) and look into standardizing the electrical communication as well.
I believe that the upcoming USB 3.1 standard is looking to target laptops for this. According to Wikipedia this will handle up to 100 watts, making it a prime candidate for a standard power source for medium or lower laptops. That would be a major improvement over the replacement power supplies with their dozen or so replaceable tips.
I guess the problem still remains that we will need to carry individual USB cord to connect from mobile to power device. The only satisfaction can be the little weight reduction in the bag but not that helpful for those who carry more than one mobile or someone who has accidently forgot to carry USB/charger.