Famitsu has published their own story about the Square Enix showcase at Japan Expo:
http://www.famitsu.com/news/201507/05082479.html
They have a better account of yesterday's announcement:
最後に、それぞれ感想を述べる中、堀井氏は「ひとつ発表をしたいと思います。『DQVII』、『DQVIII』のニンテンドー3DS版をフランスで出したいと思 います!」と、サプライズ発表! これには観客からも大きな喜びの声が挙がる! 一方、青海氏は「いやいや、正式発表はまだですから!」と慌てていたが? 正式 発表が待ち遠しい!
At the end of the DQ stage, Yuji Horii said "I want to announce one thing. I want to release Dragon Quest VII and VIII for 3DS in France!", to which DQ producer Ryota Aomi replied: "Wait! There is no official announcement yet!"
So it doesn't seem 100% certain at the moment but I guess Horii definitely wants to make it happen.