4 other countries are applying to join the EU ( & I'm not including Turkey) so things will only get worse. I know freedom of movement works both ways, but I doubt many of us will be applying to live in Albania or Serbia
Pre-Coup Turkey really wasn't going to join the EU anytime before the year 3000.
Serbia and Albania, perhaps are closer to joining than Turkey, but I can assure you both have a very long way to go on that front.
There are still massive issues with corruption, issues remaining from the legacy of the Balkans and the unresolved status of Kosovo which Serbia still fails to recognise as an independent nation (you can't enter Kosovo from certain routes and leave by Serbia, because they treat it as if you have entered Serbia illegally. If you enter you have to return via the same route. If you fly direct into Pristina, you get a special stamp in your passport - if memory serves I think its a UN one but this might have changed and my memory might not be quite right.)
Croatia only just managed the criteria. Serbia is miles behind that point. It also has a very sizeable nationalist/pro Russian section of the population that it would need to persuade to ultimately give that up and choose the EU itself. Whilst the incentive of joining the EU is a carrot to progress and is helped along by EU investment, it still is very much not a forgone conclusion that Serbia would actually want to join the EU in the end.
That said, having seen with my own eyes a pretty speculator level of struggling from Bulgaria to Serbia of every day goods (think anything from aerosols to counterfeit tshirts to cheese) with the border guards taking backhanders (on both sides of the border) a couple of years ago (prior to the migrant crisis) and what was in the shops, its pretty clear there is a massive demand to have access to tariff free trade (unless of course you are a smuggler or a border guard making a killing out of it).
And having seen this myself, I find it difficult to comprehend why we would even consider the reinstatement of such trade barriers.
I found my time travelling through Serbia an interesting experience in how the UK is treated to its own good dose of propaganda. I was told that I would be treated with hostility and as if I was a spy before going. A lot of people asked if we were scared to go.
The reality: it was one of the friendliest places I've ever been. (Though Belgrade is a bit of a dump, but then that's what being part if Yugoslavia, facing a war and then sanctions tends to do to a place) People bent over backwards to make us feel welcome in a way I've never experienced anywhere else, inviting us to friends and showing us around. Why? Because we were British and they were so amazingly proud of their country that they wanted to show us the 'real Serbia'. They were used to German tourists, but Brits were really unusual.
It was a trip that really opened my eyes to my own preconceptions and prejudices.
I also saw a lot of neo Nazis and love for Hitler which was at the time, really rather alarming, but it seems now that Serbia really isn't alone in these attitudes is it? There was also a lot of 'anti-western sentiment' and support for figures like Gaddafi, Mao and Stalin which was scary - but then what do you expect from a town that was bombed by NATO in living memory?
So to say that Serbia (and Albania) are about to join the EU makes for a nice little scaremongering story that appeals to certain people but completely bares no resemblance to the reality. It shows up people who quite happily live in their own bubble and don't question anything, rather than looking at the actual progress of EU membership (its completed 0 out of the 35 chapters - Turkey has/had 1 out of 35 though the work needed to change that is/was considerably less for Serbia than it is for Turkey).
As is always the case, never let the truth get in the way of a good Daily Mail headline.