That's the best example of all. The fair usage policy is supposed to prevent abuse and to encourage consumers to have their mobile service based in their country of residence. People in border areas will be very hard to accommodate in the FUP, yet these are one of the groups that the European Commission wants to protect.

Like the entire country of Belgium?

Not at all. More than 99% of Belgium is not in a border area capable of receiving a signal from a neighbouring country. The smallest EEA country is Liechtenstein, which might be a better example. However, it has mountains between itself and Austria, the next EEA country. Its flat and open border is with Switzerland, a non-EEA country. Remember that EU roaming regulations apply throughout the EEA, not only to the EU. Gibraltar is another good example, which is part of the EU (and EEA).

but to its size and geographical position you tend to be in roaming more often than a typical french or spanish mobile user.

Pure mathematics: the smaller the country, more of its area (in percentage) is close to the border ;)

When there is a city close to the border (Strasbourg, Frankfurt/Oder Salzburg, Bodensee area, Badajoz,...) the amount of people that are often crossing the border and suffer from roaming prices is very high.

It's not as simple as that. It depends on the shape of the country and the length of its coastline. Look at Denmark for example. The inadvertent cross-border roaming issue is also affected by mountains. Many countries' borders are formed by mountains. It's definitely not down to maths but a whole range of factors. Belgium is not a good example. Luxembourg is a much better example.

Coming back to the main issue. We should be aware, that we ALL, not only people in boarder areas, may win or lose because of the new policy depending on where we call to.

We still have to wait for the fineprint, but one thing seems to be clear: The EU shifts from a system of price caps to limited surcharges allowed on domestic rates for roaming in 2016. These surcharges may finally disappear under certain new general limits in 2017. That's all we know for sure so far.

There is one problem for everybody, no matter where he lives in the EU/EEA. All calls will be charged according to the local tariff of the provider (plus a possible surcharge in 2016/7). Undoubtly, the EU cap right now reduces drastically the rates when you call on roaming "home", within the roaming country and to another EU country.

Calling "home" may even get cheaper, because you can use your domestic allowance for it, as the EU suggested. But what about the other group of calls? Within the roaming country and to a 3rd EU country? According to the new rules, these calls will be charged based on the internatl. tariff of the provider and possibly not capped anymore. That's the same what they charge when you call from home to another EU country.

Here is a price quote of the leading networks of the UK, France and Germany on prepaid/PAYG plans as standard rate for international calls and SMS placed from this "home" country anywhere in the EU:
UK: EE - pay as you go: £1/min; SMS: 25p
Germany: Telekom - Xtra Card Auslandstarif: €1.99/min; SMS: 19ct
France: Orange - Mobicarte: €0.70/min; SMS: 28ct

Right now, all EU calls are capped at 0.19 ct/min and SMS at 6 ct plus tax.

Again, according to your home provider, calls on roaming within the roaming country and to a 3rd country are international calls charged the same as being called from "home". These calls will face a steep price increase, if the system is shifted from caps and only local tariffs are to be applied. Quote from the press statement: "It means that from 15 June 2017 you can use your mobile device when travelling in the EU paying the same prices as at home (domestic prices)."
Well, sometimes, it's not such a good idea.

UPDATE: Good News

Today the EU Parliament approved the new roaming regulations which is not a big surprise as they wanted to get rid of the surcharges even earlier.

New details about the regulations for 2016 and 2017 have emerged:
Source: http://www.consilium.europa.eu/en/pr...aming-charges/

For the regulation effective 2017:

1.) There will be a Fair Use Policy in place from 2017. This is to prevent "abusive use" of roaming whatever this may be. The new limits of this FUP will be established in Dec 2016.

2.) The new fee for overuse which is going to be imposed can't be very high as it "cannot be higher than the maximum wholesale rate that operators pay for using the networks of other EU countries."

For the regulation effective 2016:

1.) A new rate of incoming roaming for calls will be set at the end of 2015: For calls received, the maximum surcharge will be the weighted average of maximum mobile termination rates across the EU.

2.) The existing caps of 2014 will stay in place for the new rules in 2016: Also after 30 April 2016, the sum of the domestic price and any surcharge cannot in any case be higher than the current retail caps (€0.19 per minute for calls, €0.06 for texts and €0.20 per megabyte of data).

So the fear of price increases for calls within the roaming country and a third country within the EU as told in my contribution above seems to be unfounded.

The EP passed the end of roaming and net neutrality rules today.

So it's suppose to happen after 15 June 2017. From April 2016, the roaming charges for data will be .05€ per MB, not including VAT. So that's like 50€ per gigabyte before tax.

They will define fair use rules so roaming can't be abused with "permanent roaming" by EU citizens buying a SIM in another country and using it at home.

The press release talks about a citizen having her usual bundle of minutes, texts and data and while roaming, having them automatically deducted while roaming, as if they were on their domestic network.

So it sounds like this would only be for postpaid, not prepaid?

Also, postpaid plans in the EU still ration minutes and texts? In the US now, voice and SMS are unlimited because most users now use things like Whatsapp, Skype, iMessage, etc.

No, it makes no difference whether payment is in advance or in arrears. It also makes no difference whether charges are 1KB increments (common on prepaid) or 1GB increments (common on postpaid). Domestic charges must apply to intra-EEA roaming (subject to interim capped surcharges).