A little background on the latter: In September of last year the EU agreed to a 'migrant quota' whereby some 160,000 "migrants" trapped in Greece, Italy and Spain would be resettled to countries throughout the Eurozone. Thus far, not even 1,000 of those "migrants" have been settled because the countries which 'agreed' to the deal have dragged their feet on the matter.
Fast forward to now. The EU is planning on deporting an unspecified number of trapped and rejected asylum seekers back to Turkey. In exchange, Europe will resettle, within the EU, a number of asylum seekers camped in Turkey. It is assumed this will be a 1-for-1 deal, and I've heard it will involve around 70,000 people, all of whom would be rejected asylum seekers from EU countries. In addition, Turkey will get 'accelerated talks' for visa-free travel within the EU.
But here's the problem: How are the 'migrants' from Turkey going to be resettled? Which European countries are going to take them? Judging by the previous 'resettlement agreement,' it appears that NONE of them will want to take the migrants. For countries like France, Belgium, Finland, Poland, and the Czechs, who have taken relatively few 'migrants,' it's much easier to not take any of them. In effect, that's what those countries HAVE been doing thus far with the previous agreement. Is there any indication they will behave differently this time? I don't think so.
'Migrant' arrivals in Greece have dropped dramatically in March.
That leaves Germany, Austria and Sweden to directly take most of the 'resettled' migrants in exchange for their rejected ones. That may end up being what happens, but that isn't going to be a "European solution," but rather a 'solution' where the most idiotic liberal countries once again do all the heavy lifting.
Also, the 45,000 'migrants' trapped in Greece are 'expected' to be resettled in Greece, as per the September 2015 agreement.
As for Turkey joining the EU, Cyprus already vowed to veto any efforts. France has been the country traditionally blocking any movement on liberalization with Turkey, and I fully expect France to object to visa-free travel for Turkish citizens. That in and of itself could end this entire deal.
In summary, there's a very good chance the Turkey-EU deal does not even go through. If it does go through, there's an even greater chance that EU nations will drag their feet. If anything meaningful does come of this deal, it will almost certainly involve a swap of asylum seekers to and from Germany, Austria and Sweden only.
More important is the fate of the 40,000 or so 'migrants' stuck in Greece. They are NOT expected to be returned to Turkey. If these 'migrants' end up being resettled, then we should expect more of them to show up and expect the same thing, and this drop in 'migrant' arrivals will only be temporary.