Yeah, I did have one person mention that, but even they after reading it a couple times backed off that arguement. In response I pointed out that if it was really that simple, why did the WT change this in 1995 - right after they changed the whole generation meaning? If breaking it up was the intended reading, no change would have been required - and the timing shows that the policy shift was in full swing. There is no comma, and the reading flows with the understanding at the time. The sentence structure here really makes clear the one clear thought being conveyed.
I agree that if a JW wants to reason themselves around something like this, they will. I've just had some very good success - and its probably the most direct point I have found yet - as you know getting cut off is the biggest issue. So many other points take a while to get through, and the gravity of stating what God's promise is makes people think a bit harder on this. What resonates with a reasonable JW is that they have heard the argument so many times the WT does not "speak" for Jehovah - therefore they are not a false prophet. Here, they clearly say this is the creator's promise. Tough to get around.