That's because it was a particularly silly comment.
No, anything is not possible. One can tell from your comparisons that you don't actually know much about the subject, which is why people are poking at your conclusion.
Dragon Quest is the best-selling RPG in Japan, quite literally by a margin of more than 2x over the nearest competitor. It is purchased by a broad demographic: kids, teenagers, elderlies, parents, on and on. Its entire purpose for existence is to sell to the broadest conceivable demographic, which is why literally every main-series entry ever has been released on the system that was judged to have the biggest userbase in Japan at the time of release, regardless of all other factors. That's why we saw 9 go to DS -- it was just more successful than any home console, so it was the only place the series could really go.
It is not a technologically-driven franchise. It is not a franchise whose direction is driven by "Square-Enix" in the first place, but rather by its creator, Yuji Horii. He's made it clear over time the process by which the series' platform is picked, and has been 100% consistent in following that process throughout the series' history. If the game does not come out on Wii (but it almost certainly will) it would only be because it was releasing late enough that Wii was no longer a system that it could be assumed "everyone" in Japan had access to, and some new system had usurped that position. The PS3, no matter what happens, can never and will never be in the position to receive a DQ main series title.