I start to believe that too, sometimes. I mean, there will be the fight(?) against the Boss and the taking down of the BO (Vermouth dying dressed up as Ran, thus helping her one more time...sorry I had to write this XD) and Conan will finally tell the obvious to Ran that he is Shinichi, but... what about the antidote?
It seems very unstable and Shinichi's body is super resistent, it takes him less and less time to turn back to Conan. 24 hours, 12 hours, now 8 hours. I think Ai is being too kind to him by lending a hand in turning back. She likes him, so she thinks he better enjoy his "lost teenage world" for a little longer, it's like keeping Shinichi happier a bit longer until the bitter, true reality checks in. If he is lucky, he won't stay at the age of 7 permanently. We still don't know whether the drug was intended to make someone relive his/her youth or make them stuck at that age. And with the change of Vermouth's drawing style it is, again, pretty hard to guess whether she aged at all or not.
It's not unthinkable that he will have to wait 10+ years to be together with Ran. Afterall, the almost same thing happened in Yaiba too. Although the age gap was a bit smaller. And Chotto matte (Gosho's other work) is also about waiting for someone, while the other doesn't age.